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ZSHCOMPSYS(1)           FreeBSD General Commands Manual          ZSHCOMPSYS(1)

NAME
       zshcompsys - zsh completion system

DESCRIPTION
       This describes the shell code for the new completion system.  It
       consists of various shell functions; those beginning `comp' are to be
       called directly by the user, while those beginning `_' are called by
       the completion code.  The shell functions of the second set which
       implement completion behaviour and which may be bound to keystrokes,
       are referred to as `widgets'.

INITIALIZATION
       If the system was installed completely, it should be enough to call the
       shell function compinit from your initialization file; see the next
       section.  However, the function compinstall can be run by a user to
       configure various aspects of the completion system.

       Usually, compinstall will insert code into .zshrc, although if that is
       not writable it will save it in another file and tell you that file's
       location.  Note that it is up to you to make sure that the lines added
       to .zshrc are actually run; you may, for example, need to move them to
       an earlier place in the file if .zshrc usually returns early.  So long
       as you keep them all together (including the comment lines at the start
       and finish), you can rerun compinstall and it will correctly locate and
       modify these lines.  Note, however, that any code you add to this
       section by hand is likely to be lost if you rerun compinstall, although
       lines using the command `zstyle' should be gracefully handled.

       The new code will take effect next time you start the shell, or run
       .zshrc by hand; there is also an option to make them take effect
       immediately.  However, if compinstall has removed definitions, you will
       need to restart the shell to see the changes.

       To run compinstall you will need to make sure it is in a directory
       mentioned in your fpath parameter, which should already be the case if
       zsh was properly configured as long as your startup files do not remove
       the appropriate directories from fpath.  Then it must be autoloaded
       (`autoload -U compinstall' is recommended).  You can abort the
       installation any time you are being prompted for information, and your
       .zshrc will not be altered at all; changes only take place right at the
       end, where you are specifically asked for confirmation.

   Use of compinit
       This section describes the use of compinit to initialize completion for
       the current session when run directly by the user; if you have run
       compinstall it will be called automatically from your .zshrc.

       To initialize the system, the function compinit should be in a
       directory mentioned in the fpath parameter, and should be autoloaded
       (`autoload -U compinit' is recommended), and then run simply as
       `compinit'.  This will define a few utility functions, arrange for all
       the necessary shell functions to be autoloaded, and will then re-define
       all widgets that do completion to use the new system.  If you use the
       menu-select widget, which is part of the zsh/complist module, you
       should make sure that that module is loaded before the call to compinit
       so that that widget is also re-defined.  If completion styles (see
       below) are set up to perform expansion as well as completion by
       default, and the TAB key is bound to expand-or-complete, compinit will
       rebind it to complete-word; this is necessary to use the correct form
       of expansion.

       Should you need to use the original completion commands, you can still
       bind keys to the old widgets by putting a `.' in front of the widget
       name, e.g. `.expand-or-complete'.

       To speed up the running of compinit, it can be made to produce a dumped
       configuration which will be read in on future invocations; this is the
       default, although it can be turned off by calling compinit with the
       option -D.  The dumped file is .zcompdump in the same directory as the
       startup files (i.e. $ZDOTDIR or $HOME); alternatively, an explicit file
       name can be given by `compinit -d dumpfile'.  On the next call to
       compinit, it will read the dumped file instead of performing a full
       initialization.

       If the number of completion files changes, compinit will recognise this
       and produce a new dump file.  However, if the name of a function or the
       arguments in the first line of a #compdef function (as described below)
       change, it is easiest to delete the dump file by hand so that compinit
       will re-create it the next time it is run.  The check performed to see
       if there are new functions can be omitted by giving the option -C.  In
       this case the dump file will only be created if there isn't one
       already.

       The dumping is actually done by another function, compdump, but you
       will only need to run this yourself if you change the configuration
       (e.g. using compdef) and then want to dump the new one.  The name of
       the old dumped file will be remembered for this purpose.

       If the parameter _compdir is set, compinit uses it as a directory where
       completion functions can be found; this is only necessary if they are
       not already in the function search path.

       For security reasons compinit also checks if the completion system
       would use files not owned by root or by the current user, or files in
       directories that are world- or group-writable or that are not owned by
       root or by the current user.  If such files or directories are found,
       compinit will ask if the completion system should really be used.  To
       avoid these tests and make all files found be used without asking, use
       the option -u, and to make compinit silently ignore all insecure files
       and directories use the option -i.  This security check is skipped
       entirely when the -C option is given.

       The security check can be retried at any time by running the function
       compaudit.  This is the same check used by compinit, but when it is
       executed directly any changes to fpath are made local to the function
       so they do not persist.  The directories to be checked may be passed as
       arguments; if none are given, compaudit uses fpath and _compdir to find
       completion system directories, adding missing ones to fpath as
       necessary.  To force a check of exactly the directories currently named
       in fpath, set _compdir to an empty string before calling compaudit or
       compinit.

   Autoloaded files
       The convention for autoloaded functions used in completion is that they
       start with an underscore; as already mentioned, the fpath/FPATH
       parameter must contain the directory in which they are stored.  If zsh
       was properly installed on your system, then fpath/FPATH automatically
       contains the required directories for the standard functions.

       For incomplete installations, if compinit does not find enough files
       beginning with an underscore (fewer than twenty) in the search path, it
       will try to find more by adding the directory _compdir to the search
       path.  If that directory has a subdirectory named Base, all
       subdirectories will be added to the path.  Furthermore, if the
       subdirectory Base has a subdirectory named Core, compinit will add all
       subdirectories of the subdirectories is to the path: this allows the
       functions to be in the same format as in the zsh source distribution.

       When compinit is run, it searches all such files accessible via
       fpath/FPATH and reads the first line of each of them.  This line should
       contain one of the tags described below.  Files whose first line does
       not start with one of these tags are not considered to be part of the
       completion system and will not be treated specially.

       The tags are:

       #compdef names...
              The file will be made autoloadable and the function defined in
              it will be called when completing names, each of which is either
              the name of a command whose arguments are to be completed or one
              of a number of special contexts in the form -context- described
              below for the _complete function.

              Each name may also be of the form `cmd=service'.  This is used
              by functions that offer multiple services, i.e. different
              completion behaviour for multiple commands.  Such a string makes
              the completion system call the function when completing
              arguments for the command `cmd', setting the parameter $service
              to the string `service'.  The function can then use that
              parameter to decide what to complete.

       #compdef -p pattern
              The file will be made autoloadable and the function defined in
              it will be called when completing for a command whose name
              matches the given pattern (a standard globbing pattern).  Note
              that only one pattern may be given.

       #compdef -P pattern
              Like the previous one, but the function will be called only if
              no completion function for the command on the line could be
              found.

       #compdef -k style key-sequences...
              This can be used to bind special completion functions to the
              key-sequences specified.  It creates a widget behaving like the
              builtin widget style, which must be one of those that perform
              completion, namely complete-word, delete-char-or-list,
              expand-or-complete, expand-or-complete-prefix, list-choices,
              menu-complete, menu-expand-or-complete, or
              reverse-menu-complete.  If the zsh/complist module is loaded
              (see zshmodules(1)), the same happens to the menu-select widget.

              The widget is then bound to all the key-sequences given, if any:
              when one of the key-sequences is typed, the function in the file
              will be invoked to generate the matches.  Note that a key will
              not be re-bound if if it already was (that is, was bound to
              something other than undefined-key).  The widget created has the
              same name as the file and can be bound to any other keys using
              bindkey as usual.

       #compdef -K widget-name style key-sequences ...
              This is similar to -k, with the same style and key-sequences
              arguments, preceded by a string giving the name of a widget.  In
              this case only one key-sequences argument may be given, but the
              entire set of three arguments may be repeated with a different
              set of arguments.  In particular, the widget-name must be
              distinct in each set.  It should begin with `_', else one will
              be added, and should not clash with the name of any existing
              widget: names based on the name of the function are most useful.
              For example,

                     #compdef -K _foo_complete complete-word "^X^C" \
                       _foo_list list-choices "^X^D"

              (all on one line) defines a widget _foo_complete for completion,
              bound to `^X^C', and a widget _foo_list for listing, bound to
              `^X^D'.

       #autoload [ options ]
              This is used for files defining utility functions that are not
              to be called directly as completion functions but should be
              loaded automatically when invoked.  Typically they are to be
              called from within one of the completion functions.

              The options will be given to the autoload builtin command when
              making the function autoloaded.  Most often, this will be +X to
              force the function to be loaded immediately.  Note that the -U
              flag is always implicitly added.

       The # is part of the tag name and no white space is allowed after it.
       The #compdef tags use the compdef function described below; the main
       difference is that the name of the function is supplied implicitly.

       Note also that the functions for the completion system assume that the
       KSH_AUTOLOAD option is not set and cannot be loaded when it is set.  To
       avoid having to unset KSH_AUTOLOAD, you can instead use one or more zwc
       file(s) which have been created with the command zcompile -z to load
       the functions for the completion system; see zshbuiltins(1).  This
       forces the functions to be autoloaded the way zsh normally loads
       functions.

   Functions
       The compinit file defines the following function, which may also be
       called directly by the user.

       compdef [ -an ] function names...
       compdef -d names...
       compdef -p [ -a ] function pattern
       compdef -P [ -a ] function pattern
       compdef -k [ -an ] function style key-sequences...
       compdef -K [ -an ] function name style key-sequences ...
              The first form tells the completion system to call the given
              function when completing for the contexts or commands whose
              names are given:  this is like the #compdef tag unless the first
              word contains an equal sign.  In this case all words have to be
              of the form `cmd=service' where service is the name of a command
              or of a service defined by an autoloaded function with the
              #compdef tag and an argument of the form `cmd=service'.  This
              kind of use makes the arguments of the cmds be completed as
              those for the services.

              If the -n option is given, any existing completion behaviour for
              particular contexts or commands will not be altered.  These
              definitions can be deleted by giving the -d option as in the
              second form.

              The form with -p is similar to the first, but function will be
              called for all commands whose name matches the pattern; this is
              like the #compdef -p function tag.

              The form with -P is like the third, but the function will be
              called only if no function for the command itself was found or
              if one was found and it set the _compskip parameter to a value
              not containing the substring patterns.

              The form with -k defines a widget with the same name as the
              function which will be called for each of the key-sequences;
              this is like the #compdef -k tag.  The function should generate
              the completions needed and will otherwise behave like the
              builtin widget whose name is given as the style argument. The
              widgets usable for this are: complete-word, delete-char-or-list,
              expand-or-complete, expand-or-complete-prefix, list-choices,
              menu-complete, menu-expand-or-complete, and
              reverse-menu-complete, as well as menu-select if the
              zsh/complist module is loaded.  The option -n prevents the key
              being bound if it is already to bound to something other than
              undefined-key.

              The form with -K is similar and defines multiple widgets based
              on the same function, each of which requires the set of three
              arguments name, style and key-sequences, where the latter two
              are as for -k and the first must be a unique widget name
              beginning with an underscore.

              In each of the forms supporting it the -a option makes the
              function autoloadable (exactly equivalent to autoload -U
              function).

       The compdef function is the place to turn to when one wants to define
       what the completion system should complete for a certain command.  The
       function named can of course be one of the functions supplied or one
       written by the user.  For example, if one has a command foo that gets
       process identifiers as arguments, one could do:

              compdef _pids foo

       using the _pids function from the distribution to generate the process
       identifiers.  Not also the _gnu_generic function described below, which
       can be used to complete options for commands that understand the
       `--help' option.

COMPLETION SYSTEM CONFIGURATION
       This section gives a short overview of how the completion system works,
       and then more detail on how users can configure how and when matches
       are generated.

   Overview
       When completion is attempted somewhere on a command line the completion
       system first tries to find out the context where completion was tried.
       The context depends on such things as the name of the command when
       completing an argument, and possibly also the name of an option when
       completing an argument to that option.

       The `context' of a completion is a string consisting of multiple
       fields. This is used to look up styles that can be used to configure
       the completion system.  Since it is not possible to build the whole
       context string in advance, completion functions may modify some of the
       fields and hence the context used for lookup may vary during the same
       call to the completion system.

       The context string always consists of the following fields, separated
       by colons and with a leading colon before the first:

       o      The literal string completion, saying that this style is used by
              the completion system.

       o      The function; in many cases this field will be blank, but when
              the completion system is called from other functions, like
              predict-on or one of the functions in the Command directory of
              the distribution, this field contains the name of that function,
              often in an abbreviated form.

       o      The completer currently active, which is the name of the
              function without the leading underscore.  A `completer' is in
              overall control of how completion is to be performed; `complete'
              is the basic one for ordinary completion, but completers may
              perform various related tasks such as correction, or modify the
              behaviour of a later completer (see the section `Control
              Functions' below for more information).

       o      The context or command.  This is either one of the special
              context names such as -condition- as explained for the _complete
              completer below, or the name of the command we are completing
              arguments for.  Completion functions for commands that have
              sub-commands usually modify this field to contain the name of
              the command followed by a minus sign and the sub-command (e.g.
              the completion function for the cvs command sets this field to
              strings such as cvs-add when completing for the add
              sub-command).

       o      The argument, describing which argument we are completing.
              Normally this is either a string of the form argument-n, where n
              is the number of the argument or it is a string of the form
              option-opt-n when completing the n'th argument of the option
              opt.

       o      The tag.  Tags are used to discriminate between the types of
              matches a completion function can generate in a certain context.

       As an example, the context name

              :completion::complete:dvips:option-o-1:files

       says that normal completion was attempted on an argument of the dvips
       command (more precisely: completion was attempted on the first argument
       after the -o option) and the completion function will generate
       filenames for this context.

       In many of the possible contexts the completion system can generate
       matches, often multiple types of matches.  These types are represented
       as simple names called `tags'.  The completion system will decide
       internally what sort of tags are allowed; a list of the standard
       possibilities is given below.  To determine in which order the tags are
       to be used by the completion function, the `tag-order' style for the
       appropriate context may be set, as described in the list of standard
       styles below.  Only those types of matches whose tags were selected by
       this style will be produced, and in the order given, although the
       default is to try all relevant tags in an order determined by the
       particular completion in use.

       The _complete_help bindable command described in the section `Bindable
       Commands' below can be invoked to find out the context and tag names
       and styles used at a particular point in completion.  It shows the list
       of contexts and tags that would be used in if completion were tried at
       the current cursor position.  Hence one can easily find out all the
       information needed to change the behaviour of the tag-order style for a
       particular context.

       Completion behaviour can be modified by various other styles defined
       with the zstyle builtin command (see zshmodules(1)).  When looking up
       styles the completion system uses full context names, including the
       tag.

       Styles determine such things as how the matches are generated; some of
       them correspond to shell options (for example, the use of menu
       completion), but styles provide more specific control.  They can have
       any number of strings as their value.  Looking up the value of a style
       therefore consists of two things:  the context, which may be matched as
       a pattern, and the name of the style itself, which must be given
       exactly.

       For example, many completion functions can generate matches in a simple
       and a verbose form and use the verbose style to decide which form
       should be used.  To make all such functions use the verbose form, put

              zstyle ':completion:*' verbose yes

       in one of the startup files like .zshrc; this sort of style can also be
       configured with the compinstall function.  This definition simply means
       that the verbose style has yes as its value in every context inside the
       completion system.  If the context pattern were `*', the verbose style
       would have this value anywhere the style mechanism is used, not just in
       completion.

       As a more specific example, the completion function for the kill
       builtin command uses the verbose style to decide if jobs and processes
       are listed only as job numbers and process identifiers or if they are
       listed with the full job texts and the command lines of the processes
       (the latter is achieved by calling the ps command).  To make this
       builtin list the matches only as numbers one could call:

              zstyle ':completion:*:*:kill:*' verbose no

       Furthermore, if one wanted to see the command lines for processes but
       not the job texts one could use the fact that the context name contains
       the tag name when styles are looked up.  As the function for the kill
       builtin command uses the tags jobs and processes, we can use:

              zstyle ':completion:*:*:kill:*:jobs' verbose no

       To have more control over when certain values for styles are used one
       can use the special parameters available in completion widgets (see see
       zshcompwid(1))) and the -e option to zstyle that makes the value be
       evaluated when looked up.  For example, to make the completer style
       have a different value when completing for the cvs command, one could
       use the words special array:

              zstyle -e ':completion:*' completer '
                  if [[ $words[1] = cvs ]]; then
                    reply=(_complete)
                  else
                    reply=(_complete _approximate)
                  fi'

       One should be careful not to use too complicated code with this option,
       at least for the styles that are looked up quite often.  These are
       basically those that define some global completion behaviour but allow
       that to be different for all matches or groups of matches (such as the
       menu and list-rows-first styles).  Alternatively one can always use a
       less general pattern for the context than in the example above and use
       a second call to zstyle with a generic pattern and without using the -e
       option to define the default behaviour.

       Note that the order in which styles are defined does not matter; the
       style mechanism uses the most specific possible match for a particular
       style to determine the set of values.  More precisely, strings are
       preferred over patterns (for example, `:completion::complete:foo' is
       more specific than `:completion::complete:*'), and longer patterns are
       preferred over shorter patterns.

       As with tags, completion functions can use any style they choose, so
       there can't be a complete list.  However, the following two sections
       list those tags and styles that are used in many places of the
       completion system.

   Standard Tags
       Here are the tags currently used by the completion system.  Some of
       them are only used when looking up styles and do not refer to a
       particular type of match.

       accounts
              used to look up the users-hosts style

       all-expansions
              used by the _expand completer when adding the single string
              containing all possible expansions

       all-files
              for the names of all files (as distinct from a particular
              subset, see the globbed-files tag).

       arguments
              when an argument of a command may be completed

       arrays for names of array parameters

       association-keys
              for keys of associative arrays; used when completing inside a
              subscript of a parameter of this type

       bookmarks
              when completing bookmarks (e.g. for URLs and the zftp function
              suite)

       builtins
              for names of builtin commands

       characters
              used for commands like stty when completing characters; also
              used when completing character classes after an opening bracket

       colormapids
              for X colormap ids

       colors for color names

       commands
              for names of external commands and names of sub-commands (used
              by some commands like cvs)

       contexts
              for contexts used by the zstyle builtin command

       corrections
              used by the _approximate and _correct completers for the
              possible corrections

       cursors
              for cursor names used by X programs

       default
              used to look up default values for various styles that may also
              be set for tags that are used when generating matches; note that
              this tag is used when only the function field of the context
              name is set up

       descriptions
              used when looking up the value of the format style for
              descriptions

       devices
              for names of device special files

       directories
              for names of directories

       directory-stack
              for entries in the directory stack

       displays
              for X display names

       domains
              for network domains

       expansions
              used by the _expand completer for individual possibilities
              resulting from expansion of a word

       extensions
              for X server extensions

       file-descriptors
              for the numbers of open file descriptors

       files  the generic file-matching tag used by completion functions that
              can complete the names of some kind of file

       fonts  used for X font names

       functions
              names of functions, normally shell functions although certain
              commands may understand other kinds of function

       globbed-files
              for names of files matching the glob pattern used by completion
              functions that expect a certain type of file

       groups used when completing names of user groups

       history-words
              for words from the history

       hosts  for hostnames

       indexes
              used for array indexes

       jobs   used for jobs

       keymaps
              for names of zsh keymaps

       keysyms
              for names of X keysyms

       libraries
              for names of system libraries

       limits for system limits

       local-directories
              for names of directories which are subdirectories of the current
              working directory when completing for the cd and related builtin
              commands

       manuals
              for names of manual pages

       maps   for map names (e.g. NIS maps)

       messages
              used to look up the format style for messages

       modifiers
              for names of X modifiers

       modules
              for modules (e.g. zsh modules)

       my-accounts
              used to look up the users-hosts style

       named-directories
              for named directories (you wouldn't have guessed that, would
              you?)

       names  for all kinds of names

       nicknames
              for nicknames of NIS maps

       options
              for command options

       original
              used by the _approximate, _correct and _expand completers when
              adding the original string

       other-accounts
              used to look up the users-hosts style

       packages
              for packages (e.g. rpm or installed Debian packages)

       parameters
              for names of parameters

       path-directories
              for names of directories found by searching the cdpath array
              when completing for the cd and related builtin commands

       paths  used to look up the values of the expand, ambiguous and
              special-dirs styles

       pods   for perl pods (documentation files)

       ports  for communication ports

       prefixes
              for prefixes (like those of a URL)

       printers
              for printer names

       processes
              for process identifiers

       processes-names
              used to look up the command style when generating the names of
              processes for killall

       sequences
              for sequences (e.g. mh sequences)

       sessions
              for sessions in the zftp function suite

       signals
              for signal names

       strings
              for strings (e.g. the replacement strings for the cd builtin
              command)

       styles for styles used by the zstyle builtin command

       tags   for tags (e.g. rpm tags)

       targets
              for makefile targets

       types  for types of whatever (e.g. address types for the xhost command)

       urls   used to look up the urls and local styles when completing URLs

       users  for usernames

       values when completing a value out of a set of values (or a list of
              such values)

       version
              used by _call_program to look up the command to run to determine
              the installed version of various other commands (such as diff
              and make).

       warnings
              used to look up the format style for warnings

       widgets
              for zsh widget names

       windows
              for IDs of X windows

       zsh-options
              for shell options

   Standard Styles
       Here are the names of the styles used by the completion system.  Note
       that the values of several of these styles represent boolean values;
       here, any of the strings `true', `on', `yes', and `1' can be used for
       the truth value `true' and the strings `false', `off', `no', and `0'
       are interpreted as `false'.  The behavior for any other value is
       undefined unless the description for the particular style mentions
       other possible values; in particular, the default value may be either
       on or off if the style is not set.

       Some of these styles are tested for every tag used to add possible
       matches and for the default tag (most notably menu, list-colors and the
       styles controlling the completion listing like list-packed and
       last-prompt). When tested for the default tag, only the function field
       of the context will be set up, so the default value will normally be
       set like:

              zstyle ':completion:*:default' menu ...

       accept-exact
              This is tested for the default tag and the tags used when
              generating matches.  If it is set to `true' for at least one
              match which is the same as the string on the line, this match
              will immediately be accepted.

              When completing pathnames (where it is looked up for the paths
              tag), this style also accepts any number of patterns as the
              value. If this is used, pathnames matching one of these patterns
              will be accepted immediately even if the command line contains
              some more partially typed pathname components and these match no
              file under the directory accepted.

              Note that this is also used by the _expand completer to decide
              if words beginning with a tilde or parameter expansion should be
              expanded. This means that if, for example, there are parameters
              foo and foobar, the string `$foo' will only be expanded if
              accept-exact is set to `true'.

       add-space
              This style is used by the _expand completer.  If it is `true'
              (the default), a space will be inserted after all words
              resulting from the expansion (except for directory names which
              get a slash).  The value may also be the string `file' to make
              the completer add a space only to names of existing files.
              Finally, the `true' values and `file' may be combined with
              `subst' to keep the completer from adding a space when the
              resulting words were generated by expanding a substitution of
              the form `$(...)' or `${...}'.

              It is also used by the _prefix completer as a simple boolean
              value to decide if a space should be inserted before the suffix.

       ambiguous
              This applies when completing non-final components of filename
              paths.  If it is set, the cursor is left after the first
              ambiguous component, even if menu completion is in use.  It is
              tested with the paths tag.

       assign-list
              When completing after an equals sign, the completion system
              normally completes only one filename.  In some cases,
              particularly for certain parameters such as PATH, a list of
              filenames separated by colons is required.  This style can be
              set to a list of patterns matching the names of such parameters.

              The default is to complete lists when the word on the line
              already contains a colon.

       auto-description
              If set, this style's value will be used as the description for
              options which are not described by the completion functions, but
              that have exactly one argument.  The sequence `%d' in the value
              will be replaced by the description for this argument.
              Depending on personal preferences, it may be useful to set this
              style to something like `specify: %d'.  Note that this may not
              work for some commands.

       avoid-completer
              This is used by the _all_matches completer to decide if the
              string consisting of all matches should be added to the list
              currently being generated.  Its value is a list of names of
              completers.  If any of these is the name of the completer that
              generated the matches in this completion, the string will not be
              added.

              The default value for this style is `_expand _old_list _correct
              _approximate', i.e. it contains the completers for which a
              string with all matches will almost never be wanted.

       cache-path
              This style defines the path where any cache files containing
              dumped completion data are stored.  Defaults to
              `$ZDOTDIR/.zcompcache', or `$HOME/.zcompcache' if $ZDOTDIR is
              not defined.  The completion layer will not be used unless the
              use-cache style is set.

       call-command
              Currently this is only used by the function completing make
              targets.  If it is set to `true' and the installed version of
              the make command allows it, make is called in a way to generate
              all possible targets.  The default value of this style is
              `false' because calling make can potentially take a very long
              time and in some cases may even cause actions from the makefile
              be executed despite the options given to make.

       command
              In many places, completion functions need to call external
              commands to generate the list of completions.  This style can be
              used to override the command which is called in some such cases.
              The elements of the value are joined with spaces to form a
              command line to execute.  The value can also start with a
              hyphen, in which case the usual command will be added to the
              end; this is most useful for putting `builtin' or `command' in
              front to make sure the appropriate version of a command is
              called, for example to avoid calling a shell function with the
              same name as an external command.

              As an example, the function generating process IDs as matches
              uses this style with the processes tag to generate the IDs to
              complete and the list of processes to display (if the verbose
              style is `true').  The list produced by the command should look
              like the output of the ps command.  The first line is not
              displayed, but is searched for the string `PID' (or `pid') to
              find the position of the process IDs in the following lines.  If
              the line does not contain `PID', the first numbers in each of
              the other lines are taken as the process IDs to complete.

              Note that the completion function generally has to call the
              command every time it is called.  Because of that care should be
              taken to specify only commands that take a short time to run
              (and that will eventually stop at all).

       commands
              This is used by the function completing sub-commands for the
              system initialisation scripts (residing in /etc/init.d or
              somewhere not too far away from that).  It's values give the
              default commands to complete for those commands for which the
              completion function isn't able to find them out automatically.
              The default for this style are the two strings `start' and
              `stop'.

       complete
              This is used by the _expand_alias function when invoked as a
              bindable command.  If it set to `true' and the word on the
              command line is not the name of an alias, matching alias names
              will be completed.

       completer
              The strings given as the value of this style provide the names
              of the completer functions to use. The available completer
              functions are described in the section `Control Functions'
              below.

              Each string may be the name of a completer function or a string
              of the form `function:name'. In the first case the completer
              field of the context will contain the name of the completer
              without the leading underscore and with all other underscores
              replaced by hyphens.  In the second case the function is the
              name of the completer to call, but the context will contain the
              name in the completer field of the context.  If the name starts
              with a hyphen, the string for the context will be build from the
              name of the completer function as in the first case with the
              name appended to it.  For example:

                     zstyle ':completion:*' completer _complete _complete:-foo

              Here, completion will call the _complete completer twice, once
              using `complete' and once using `complete-foo' in the completer
              field of the context.  Normally, using the same completer more
              than once makes only sense when used with the `functions:name'
              form, because otherwise the context name will be the same in all
              calls to the completer; possible exceptions to this rule are the
              _ignored and _prefix completers.

              The default value for this style is _complete _ignored, i.e.
              normally only completion will be done, first using the
              ignored-patterns style and the $fignore array and then without
              ignoring matches.

       condition
              This style is used by the _list completer function to decide if
              insertion of matches should be delayed unconditionally. The
              default is `true'.

       disabled
              If this is set to `true', the _expand_alias completer and
              bindable command will try to expand disabled aliases, too.  The
              default is `false'.

       disable-stat
              This is used with an empty tag by the function completing for
              the cvs command to decide if the zsh/stat module should be used
              to generate names of modified files in the appropriate places
              (this is its only use).  If set, completion will use the ls
              command.

       domains
              If set, gives the names of network domains that should be
              completed.  If this is not set by the user domain names will be
              taken from the file /etc/resolv.conf.

       expand This style is used when completing strings consisting of
              multiple parts, such as path names.  If one of its values is the
              string `prefix', the partially typed word from the line will be
              expanded as far as possible even if trailing parts cannot be
              completed.  If one of its values is the string `suffix',
              matching names for components after the first ambiguous one will
              also be added.  This means that the resulting string is the
              longest unambiguous string possible, but if menu completion is
              started on the list of matches generated this way, this will
              also cycle through the names of the files in pathname components
              after the first ambiguous one.

       fake-files
              This style is used when completing files and looked up without a
              tag.  Its values are of the form `dir:names...'.  This will add
              the names (strings separated by spaces) as possible matches when
              completing in the directory dir, even if no such files really
              exist.

              This can be useful on systems that support special filesystems
              whose top-level pathnames can not be listed or generated with
              glob patterns.  It can also be used for directories for which
              one does not have read permission.

       fake-parameters
              This is used by the completion function generating parameter
              names as matches.  Its values are names of parameters which
              might not yet be set, but which should be completed nonetheless.
              Each name may also be followed by a colon and a string
              specifying the type of the parameter (like `scalar', `array' or
              `integer').  If such a type is given, the name will only be
              completed if parameters of that type are requested in the
              particular context.  Names for which no type is specified will
              always be completed.

       file-patterns
              In most places where filenames are completed, the function
              _files is used which can be configured with this style.  If the
              style is unset, _files offers, one after another, up to three
              tags: `globbed-files', `directories' and `all-files', depending
              on the types of files expected by the caller of _files.

              If the file-patterns style is set, the default tags are not
              used.  Instead, the value of the style says which tags and which
              patterns are to be offered.  The strings in the value contain
              specifications of the form `pattern:tag'; each string may
              contain any number of such specifications.  The pattern gives a
              glob pattern that is to be used to generate filenames.  If it
              contains the sequence `%p', that is replaced by the pattern(s)
              given by the calling function.  Colons in the pattern must be
              preceded by a backslash to make them distinguishable from the
              colon before the tag.  If more than one pattern is needed, the
              patterns can be given inside braces, separated by commas.  The
              tags of all strings in the value will be offered by _files
              (again, one after another) and used when looking up other
              styles.  For strings containing more than one specification, the
              filenames for all specifications will be generated at the same
              try.  If no `:tag' is given the `files' tag will be used.  The
              tag may also be followed by an optional second colon and a
              description.  If that is given, this description will be used
              for the `%d' in the value of the format style (if that is set)
              instead of the default description supplied by the completion
              function.  If the description given here contains itself a `%d',
              that is replaced with the description supplied by the completion
              function.

              For example, to make the rm command first complete only names of
              object files and the names of all files if no object file
              matches the string on the line, one would do:

                     zstyle ':completion:*:*:rm:*' file-patterns \
                         '*.o:object-files' '%p:all-files'

              Another interesting example is to change the default behaviour
              that makes completion first offer files matching the patterns
              given by the calling function, then directories and then all
              files.  Many people prefer to get both the files matching the
              given patterns and the directories in the first try and all
              files at the second try.  To achieve this, one could do:

                     zstyle ':completion:*' file-patterns \
                         '%p:globbed-files *(-/):directories' '*:all-files'

              This works even for contexts in which all files would be
              completed, because _files will not try a pattern more than once
              and it stops when the pattern `*' was tried.

              Note also that during the execution of completion functions, the
              EXTENDED_GLOB option is in effect, so the characters `#', `~'
              and `^' have special meanings in the patterns.

       file-sort
              The completion function that generates filenames as possible
              matches uses this style without a tag to determine in which
              order the names should be listed and completed when using menu
              completion.  The value may be one of `size' to sort them by the
              size of the file, `links' to sort them by the number of links to
              the file, `modification' (or `time' or `date') to sort them by
              the last modification time, `access' to sort them by the last
              access time, or `inode' (or `change') to sort them by the last
              inode change time.  If the style is set to any other value, or
              is unset, files will be sorted alphabetically by name.  If the
              value contains the string `reverse', sorting is done in
              decreasing order.

       force-list
              This forces a list of completions to be shown at any point where
              listing is done, even in cases where the list would usually be
              suppressed.  For example, normally the list is only shown if
              there are at least two different matches.  By setting this style
              to `always', the list will always be shown, even if there is
              only a single match which is immediately accepted.  The style
              may also be set to a number.  In this case the list will be
              shown if there are at least that many matches, even if they
              would all insert the same string.

              This style is tested for the default tag and all tags used when
              generating matches. This allows one to turn unconditional
              listing on for certain types of matches.

       format If this is set for the descriptions tag, its value is used as a
              string to display above matches in completion lists.  The
              sequence `%d' in this string will be replaced with a short
              description of what these matches are.  This string may also
              contain the sequences to specify output attributes, such as
              `%B', `%S' and `%{...%}'.

              For the same purpose, this style is also tested with the tags
              used when matches are generated before it is tested for the
              descriptions tag.  This provides the possibility of defining
              different format strings for different types of matches.

              Note also that some completer functions define additional
              `%'-sequences.  These are described for the completer functions
              that make use of them.

              For the messages tag, this style defines a string used by some
              completion functions to display messages.  Here, the `%d' is
              replaced with a message given by the completion function.

              Finally, when set with the warnings tag, the format string is
              printed when no matches could be generated at all.  In this case
              the `%d' is replaced with the descriptions for the matches that
              were expected separated by spaces and the sequence `%D' is
              replaced with those descriptions separated by newlines.

              The `%' for the sequences that are replaced by strings provided
              by the completion functions like the `%d' may be followed by
              field width specifications as  described for the zformat builtin
              command from the zsh/zutil module, see zshmodules(1).

       glob   This is used by the _expand completer.  If it is set to `true'
              (the default), globbing will be attempted on the words resulting
              from substitution (see the substitute style) or the original
              string from the line.

       global If this is set to `true' (the default), the _expand_alias
              completer and bindable command will try to expand global
              aliases.

       group-name
              The completion system can put different types of matches in
              different groups which are then displayed separately in the list
              of possible completions.  This style can be used to give the
              names for these groups for particular tags.  For example, in
              command position the completion system generates names of
              builtin and external commands, names of aliases, shell functions
              and parameters and reserved words as possible completions.  To
              have the external commands and shell functions listed
              separately, one can set:

                     zstyle ':completion:*:*:-command-:*:commands' group-name commands
                     zstyle ':completion:*:*:-command-:*:functions' group-name functions

              This also means that if the same name is used for different
              types of matches, then those matches will be displayed together
              in the same group.

              If the name given is the empty string, then the name of the tag
              for the matches will be used as the name of the group. So, to
              have all different types of matches displayed separately, one
              can just set:

                     zstyle ':completion:*' group-name ''

              All matches for which no group name is defined will be put in a
              group named -default-.

       group-order
              This style is to be used together with the group-name style.
              Once different types of matches are put into different groups,
              this style can be used to define in which order these groups
              should appear when listing (compare tag-order, which determines
              which completions appear at all).  The strings in the value are
              taken as group names and the named groups will be shown in the
              order in which their names appear in the value.  All groups
              whose names are not given in the value of this style will appear
              in the order defined by the function generating the matches.

              For example, to have names of builtin commands, shell functions
              and external commands appear in this order when completing in
              command position one would set:

                     zstyle ':completion:*:*:-command-:*' group-order \
                            builtins functions commands

       groups A style holding the names of the groups that should be
              completed. If this is not set by the user, the group names from
              the YP database or the file `/etc/group' will be used.

       hidden If this is set to one of the `true' values, the matches for the
              tags for which this is set will not appear in the list; only the
              description for the matches as set with the format style will be
              shown.  If this is set to `all', not even the description will
              be displayed.

              Note that the matches will still be completed; they are just not
              shown in the list.  To avoid having matches considered as
              possible completions at all, the tag-order style can be modified
              as described below.

       hosts  A style holding the names of hosts that should be completed. If
              this is not set by the user the hostnames in `/etc/hosts' will
              be used.

       hosts-ports
              This style is used by commands that need or accept hostnames and
              ports.  The strings in the value should be of the form
              `host:port'.  These hostnames and ports are completed depending
              on the information already on the line, so that if, for example,
              the hostname is already typed, only those ports specified for
              that host will be completed.  Multiple ports for the same host
              may appear.

       ignore-line
              This style is tested for the tags used when generating matches.
              If it is set to `true', then none of the words that are already
              on the line will be considered possible completions.  If it is
              set to `current', the word the cursor is on will not be
              considered a possible completion.  The same happens if the value
              is `current-shown', but only if the list of completions is
              currently shown on the screen.  Finally, if it is set to `other'
              all words except the current one will not be considered to be a
              possible completion.

              The values `current' and `current-shown' are a bit like the
              opposite of accept-exact. They mean that only strings with
              missing characters will be completed.

              Note that you almost certainly don't want to set this to `true'
              or `other' for a general context such as `:completion:*'.  This
              is because it would disallow completion of, for example, options
              multiple times even if the command in question accepts the
              option more than once.

       ignore-parents
              The style is tested by the function completing pathnames without
              a tag to determine whether to ignore the names of directories
              already mentioned in the current word, or the name of the
              current working directory.  The value must include one or both
              of the following strings:

              parent The name of any directory whose path is already contained
                     in the word on the line is ignored.  For example, when
                     completing after foo/../, the directory foo will not be
                     considered a valid completion.

              pwd    The name of the current working directory will not be
                     completed, so that, for example, completion after ../
                     will not use the name of the current directory.

              In addition, the value may include one or both of:

              ..     Ignore the specified directories only when the word on
                     the line contains the substring `../'.

              directory
                     Ignore only when names of directories are completed, not
                     when completing names of files.

              Note that names of directories ignored because of one of the
              tests will be ignored in the same way as the matches ignored
              because of the ignored-patterns style.  I.e., by using the
              _ignored completer it is possible to complete these directories
              nonetheless.

       ignored-patterns
              This style can be used to specify a list of patterns which are
              tested against against the trial completions in a given context;
              any matching completions will be removed from the list of
              possibilities.  The _ignored completer can appear in the list of
              completers to produce a list which includes these matches once
              more.  This is a more configurable version of the shell
              parameter $fignore.

              Note that during the execution of completion functions, the
              EXTENDED_GLOB option is in effect, so the characters `#', `~'
              and `^' have special meanings in the patterns.

       insert-ids
              When completing process IDs, for example as arguments to the
              kill and wait builtins, completion allows the user to type the
              name of a command, which will be converted to the appropriate
              process ID.  A problem arises when the process name typed is not
              unique.  By default (or if this style is set explicitly to
              `menu') the name will be converted immediately to a set of
              possible IDs, and menu completion will be started to cycle
              through them.  If the value of the style is `single', however,
              the shell will wait until the user has typed enough to make the
              command unique before converting the name to an ID; the user
              must type any additional characters required.  If the value is
              any other string, menu completion will be started when the
              string typed by the user is longer than the common prefix of the
              corresponding IDs.

       insert-tab
              If this has one of the `true' values, the completion system will
              insert a TAB character (assuming it was used to start
              completion) instead of performing completion when there is no
              non-blank character to the left of the cursor.  If set to
              `false', completion will be done even there.

              The value may also contain the substrings `pending' or
              `pending=val' to make the character typed to start completion be
              inserted instead of completion being tried when there is input
              pending which has not yet been processed by the shell. If a val
              is given, completion will not be done if there are at least that
              many characters of unprocessed input. This is often useful to
              have set when pasting characters into a terminal. Note however,
              that it relies on the $PENDING special parameter from the
              zsh/zle module being set properly which is not guaranteed on all
              platforms.

              The default value of this style is `true' unless when completing
              inside the vared builtin command, where it defaults to `false'.

       insert-unambiguous
              This is used by the _match and _approximate completer functions,
              where the possible completions may not have a common prefix so
              that menu completion is often the most useful may of choosing
              completions.  If the style is set to `true', the completer will
              start menu completion only if no unambiguous string could be
              generated that is at least as long as the original string typed
              by the user.  Note that the _approximate completer uses it after
              setting the completer field in the context name to one of
              correct-num or approximate-num, where num is the number of
              errors that were accepted.

              When used for the _match completer, the style may also be set to
              the string `pattern'.  This makes the pattern on the line be
              left unchanged if it didn't match unambiguously.

       keep-prefix
              This style is used by the _expand completer.  If it is `true',
              the completer will try to keep a prefix containing a tilde or
              parameter expansion.  I.e., the string `~/f*' would be expanded
              to `~/foo' instead of `/home/user/foo'.  If the style is set to
              `changed' (the default), the prefix will only be left unchanged
              if there were other changes between the expanded words and the
              original word from the command line.  Any other value makes the
              prefix be expanded unconditionally.

              Note that with one of the `true' values, the _expand completer
              returns if there is only one expansion and that is, after
              restoring the original prefix, the same as the original word.
              This means that other completers will be called immediately
              after _expand.

       last-prompt
              This is used to determine if the completion code should try to
              put the cursor back onto the previous command line after showing
              a completion listing (as for the ALWAYS_LAST_PROMPT option).  As
              with several other styles, it is tested for the default tag as
              well as all the possible tags when generating matches.  The
              cursor will be moved back to the previous line if this style is
              `true' for all types of matches added.  Note also that this is
              independent of the numeric argument, unlike the
              ALWAYS_LAST_PROMPT option.

       list   This style is used by the _history_complete_word bindable
              command.  If it is set to `true' it has no effect, but if it is
              set to `false' the matches will not be listed, overriding the
              setting of the options that control listing behaviour,
              especially AUTO_LIST. Use the context prefix
              `:completion:history-words'.

       list-colors
              If the zsh/complist module is used, this style can be used to
              set color specifications as with the ZLS_COLORS and ZLS_COLOURS
              parameters, which will not be honored under this completion
              system (see the section `The zsh/complist Module' in
              zshmodules(1)).

              If this style is set for the default tag, the strings in the
              value are taken as specifications that are to be used
              everywhere.  If it is set for other tags, the specifications are
              used only for matches of the type described by the tag.  For
              this to work best, the group-name style must be set to an empty
              string.  If the group-name tag specifies other names for the
              groups the matches in these groups can be colored by using these
              names together with the `(group)...' syntax described for the
              ZLS_COLORS and ZLS_COLOURS parameters and adding the
              specifications to the value for this style with the default tag
              (although in most cases it should work by setting this style for
              the appropriate tags).

              It is possible to use the same specifications set up for the GNU
              version of the ls command:

                     zstyle ':completion:*:default' list-colors ${(s.:.)LS_COLORS}

              The default colors are the same as for the GNU ls command and
              can be obtained by setting the style to an empty string (i.e.
              '').

       list-packed
              Like the list-colors style, this is tested with the default tag
              and all tags used when generating matches.  If it is set to
              `true' for a tag, the matches added for it will be listed as if
              the LIST_PACKED option were set.  If it is set to `false', they
              are listed normally.

       list-prompt
              If this style is set for the default tag, completion lists that
              don't fit on the screen can be scrolled (see the description of
              the zsh/complist module in zshmodules(1)).  The value, if not
              the empty string, will be displayed after every screenful and
              the shell will prompt for a key press; if the style is set to
              the empty string, a default prompt will be used.  The value may
              contain the escape sequences `%l' or `%L', which will be
              replaced by the number of the last line displayed and the total
              number of lines; `%m' or `%M', which will be replaced by the
              number of the  last match shown and the total number of matches;
              and `%p' and `%P', which will be replaced by `Top' when at the
              beginning of the list, `Bottom' when at the end and the position
              shown in percent of the total length otherwise.  In each of
              these cases the form with the uppercase letter is replaced by a
              string of fixed width, padded to the  right with spaces.  As in
              other prompt strings, the escape sequences `%S', `%s', `%B',
              `%b', `%U', `%u', and `%{...%}' for entering and leaving the
              display modes standout, bold and underline are also available.

       list-rows-first
              This style is tested in the same way as the list-packed style
              and determines if matches are to be listed in a rows-first
              fashion, as for the LIST_ROWS_FIRST option.

       list-suffixes
              This style is used by the function used to complete filenames.
              If completion is attempted on a string containing multiple
              partially typed pathname components and this style is set to
              `true', all components starting with the first one for which
              more than one match could be generated will be shown.

       local  This style is used by completion functions which generate URLs
              as possible matches to add suitable matches when a URL points to
              a local web server, that is, one whose files are available
              directly on the local file system.  Its value should consist of
              three strings: a hostname, the path to the default web pages for
              the server and the directory name used by a user placing web
              pages within their home area.  For example, completion after
              `http://toast/~yousir/' will attempt to match the name `toast'
              against the first argument to the style, and if successful will
              look in the directory under ~yousir given by the third argument
              to the style for possible completions.

       match-original
              This is used by the _match completer.  If it is set to only,
              _match will try to generate matches without inserting a `*' at
              the cursor position.  If set to any other non-empty value, it
              will first try to generate matches without inserting the `*' and
              if that yields no matches, it will try again with the `*'
              inserted.  If it is unset or set to the empty string, matching
              will only be done with the `*' inserted.

       matcher
              This style is tested for tags used when generating matches.  Its
              value is used as an match specification additional to any given
              by the matcher-list style which should be in the form described
              in the section `Matching Control' in zshcompwid(1).

       matcher-list
              This style is used by the main completion function to retrieve
              match specifications that are to be used everywhere.  Its value
              should be a list of such specifications.  The completion system
              will try them one after another for each completer selected. For
              example, to first try simple completion and, if that generates
              no matches, case-insensitive completion one would do:

                     zstyle ':completion:*' matcher-list '' 'm:{a-zA-Z}={A-Za-z}'

              By default every specification replaces previous ones. If
              specification is prefixed with +, it is added to the existing
              list. This allows testing more general patterns without
              repeating the whole list every time, as in:

                     zstyle ':completion:*' matcher-list '' '+m{a-Z}={A-Z}' '+m{A-Z}={a-z}'

              The style allows even finer control by specifying a particular
              completer, without the leading underscore, in the third field of
              the completion context.  For example, if one uses the completers
              _complete and _prefix but wants to try case-insensitive
              completion only when using the _complete completer, one would
              do:

                     zstyle ':completion:*' completer _complete _prefix
                     zstyle ':completion:*:complete:*' matcher-list \
                            '' 'm:{a-zA-Z}={A-Za-z}'

              Note that the completer style allows user-defined names to be
              used in the context instead of the name of the completer.  This
              is useful if, for example, one wants to try normal completion
              without a match specification and with case-insensitive matching
              first, correction if that doesn't generate any matches and
              partial-word completion if that doesn't yield any matches
              either.  In this case one can give the _complete completer more
              than once in the completer style and define different match
              specifications for each occurrence, as in:

                     zstyle ':completion:*' completer _complete _correct _complete:foo
                     zstyle ':completion:*:complete:*' matcher-list \
                         '' 'm:{a-zA-Z}={A-Za-z}'
                     zstyle ':completion:*:foo:*' matcher-list \
                         'm:{a-zA-Z}={A-Za-z} r:|[-_./]=* r:|=*'

              If the style is unset in any context no match specification is
              applied; further, some completers such as _correct and
              _approximate do not use the match specifications at all.
              However, it is always safe to use the simple form for this style
              (as in the first example above), since any completers which do
              not use match specifications will only ever be called once,
              rather than once per specification.

              Since the specification-strings in this style have to be tried
              one after another, it is a good idea to keep their number low.
              In most cases one to three strings (each of which may, without
              to large a performance hit, consist of more than one single
              match specification) will give acceptable performance.

       max-errors
              This is used by the _approximate and _correct completer
              functions to determine the maximum number of errors to allow.
              The completer will try to generate completions by first allowing
              one error, then two errors, and so on, until either a match or
              matches were found or the maximum number of errors given by this
              style has been reached.

              If the value for this style contains the string `numeric', the
              completer function will take any numeric argument as the maximum
              number of errors allowed. For example, with

                     zstyle ':completion:*:approximate:::' max-errors 2 numeric

              two errors are allowed if no numeric argument is given, but with
              a numeric argument of six (as in `ESC-6 TAB'), up to six errors
              are accepted.  Hence with a value of `0 numeric', no correcting
              completion will be attempted unless a numeric argument is given.

              If the value contains the string `not-numeric', the completer
              will not try to generate corrected completions when given a
              numeric argument, so in this case the number given should be
              greater than zero.  For example, `2 not-numeric' specifies that
              correcting completion with two errors will usually be performed,
              but if a numeric argument is given, correcting completion will
              not be performed.

              The default value for this style is `2 numeric'.

       menu   If this is set to true in a given context, using any of the tags
              defined for a given completion, menu completion will be used.
              The tag `default' can be used to set the default value, but a
              specific tag will take precedence.  If none of the values found
              in this way is true but at least one is set to `auto' the
              behaviour will be as for the AUTO_MENU option.  Finally, if one
              of the values is explicitly set to false, menu completion will
              be turned off even if it would otherwise be active (for example,
              with the MENU_COMPLETE option).

              Using the form `yes=num', where `yes' may be any of the true
              values (`yes', `true', `on' and `1') turns on menu completion if
              there at least num matches.  Using this for one of the `false'
              values (as in `no=10') makes menu completion not be used if
              there are num or more matches.  Of course, this is only useful
              when menu completion is normally used, e.g. by setting the
              MENU_COMPLETE option.  The `true' values may also be used in the
              form `yes=long' to turn on menu completion if the list does not
              fit onto the screen.  This will start menu completion only if
              normal completion was attempted, not when only the list of
              possible completions was requested.  To start menu completion
              even then, the value `yes=long-list' can be used.

              In addition to (or instead of) the above possibilities, the
              value may contain the string `select', optionally followed by an
              equals sign and a number.  In this case menu selection (as
              defined by the zsh/complist module) will be started.  Without
              the optional number, it will be started unconditionally and with
              a number it will be started only if at least that many matches
              are generated; if the values for more than one tag provide a
              number, the smallest number is taken.  Menu selection can be
              turned off explicitly by defining a value containing the string
              `no-select'.

              It is also possible to start menu selection only if the list of
              matches does not fit on the screen by using the value
              `select=long'.  This will only start menu selection if the
              widget invoked does completion, not simply listing as done by
              delete-char-or-list; to start menu selection even here, use the
              value `select=long-list'.

              To turn on menu completion or menu selection when a certain
              number of matches is generated or the list of matches does not
              fit onto the screen, both of `yes=' and `select=' can be given
              twice, once with a number and once with `long' or `long-list'.

       numbers
              This is used with the jobs tag.  If it is `true', the shell will
              complete the job numbers instead of the shortest unambiguous
              strings of the jobs' command lines.  If the value is a number,
              job numbers will only be used if that many words from the job
              descriptions are required to resolve ambiguities.  For example,
              if the value is `1', strings will only be used if all jobs
              differ in the first word on their command lines.

       old-list
              This is used by the _oldlist completer.  If it is set to
              `always', then standard widgets which perform listing will
              retain the current list of matches, however they were generated;
              this can be turned off explicitly with the value `never', giving
              the behaviour without the _oldlist completer.  If the style is
              unset, or any other value, then the existing list of completions
              is displayed if it is not already; otherwise, the standard
              completion list is generated; this is the default behaviour of
              _oldlist.  However, if there is an old list and this style
              contains the name of the completer function that generated the
              list, then the old list will be used even if it was generated by
              a widget which does not do listing.

              For example, suppose you type ^Xc to use the _correct_word
              widget, which generates a list of corrections for the word under
              the cursor.  Usually, typing ^D would generate a standard list
              of completions for the word on the command line, and show that.
              With _oldlist, it will instead show the list of corrections
              already generated.

              As another example consider the _match completer: with the
              insert-unambiguous style set to `true' it inserts only a common
              prefix string, if there is any.  However, this may remove parts
              of the original pattern, so that further completion could
              produce more matches than on the first attempt.  By using the
              _oldlist completer and setting this style to _match, the list of
              matches generated on the first attempt will be used again.

       old-matches
              This is used by the _all_matches completer to decide if an old
              list of matches should be used if one exists.  It may be set to
              one of the `true' values or to the string `only' to use such a
              list.  If it is set to `only', _all_matches will only use an old
              list and won't have any effect on the list of matches currently
              being generated.

       old-menu
              This is used by the _oldlist completer.  It controls how menu
              completion behaves when a completion has already been inserted
              and the user types a standard completion key type such as TAB.
              The default behaviour of _oldlist is that menu completion always
              continues with the existing list of completions.  If this style
              is set to `false', however, a new completion is started if the
              old list was generated by a different completion command; this
              is the behaviour without the  _oldlist completer.

              For example, suppose you type ^Xc to generate a list of
              corrections, and menu completion is started in one of the usual
              ways.  Usually, or with this style set to false, typing TAB at
              this point would start trying to complete the line as it now
              appears.  With _oldlist, it instead continues to cycle through
              the list of corrections.

       original
              This is used by the _approximate and _correct completers to
              decide if the original string should be added as one possible
              completion.  Normally, this is done only if there are at least
              two possible corrections, but if this style is set to `true', it
              is always added.  Note that these completers use this style
              after setting the completer field in the context name to
              correct-num or approximate-num, where num is the number of
              errors that were accepted.

       packageset
              This style is used when completing arguments of the Debian
              `dpkg' program.  It contains an override for the default package
              set for a given context.  For example,

                     zstyle ':completion:*:complete:dpkg:option--status-1:*' \
                                    packageset avail

              causes available packages, rather than only installed packages,
              to be completed for `dpkg --status'.

       path   The function that completes color names uses this style with the
              colors tag.  The value should be the pathname of a file
              containing color names in the format of an X11 rgb.txt file.  If
              the style is not set but this file is found in one of various
              standard locations it will be used as the default.

       ports  A style holding the service names of ports to complete.  If this
              is not set by the user, the service names from `/etc/services'
              will be used.

       prefix-hidden
              This is used when matches with a common prefix are added (e.g.
              option names).  If it is `true', this prefix will not be shown
              in the list of matches.

              The default value for this style is `false'.

       prefix-needed
              This, too, is used for matches with a common prefix.  If it is
              set to `true' this common prefix has to be typed by the user to
              generate the matches.  E.g. for options this means that the `-',
              `+', or `--' has to be on the line to make option names be
              completed at all.

              The default value for this style is `true'.

       preserve-prefix
              This style is used when completing path names.  Its value should
              be a pattern matching an initial prefix of the word to complete
              that should be left unchanged under all circumstances.  For
              example, on some Unices an initial `//' (double slash) has a
              special meaning and hence should be kept.  For that one could
              set this style to the string `//'.  As another example, setting
              this style to `?:/' under Cygwin would allow completion after
              `a:/...' and the like.

       range  This is used by the _history completer and the
              _history_complete_word bindable command to decide which words
              should be completed.  It may be set to a number, N, to say that
              only the last N words from the history should be completed.  The
              value may also be of the form `max:slice'.  This means that
              first the last slice words will be completed.  If that yields no
              matches, the slice words before those will be tried and so on,
              until either at least one match is generated or max words have
              been tried.  The default is to complete all words from the
              history at once.

       regular
              This style is used by the _expand_alias completer and bindable
              command.  If set to `true' (the default), regular aliases will
              be expanded but only in command position.  If it is set to
              `false', regular aliases will never be expanded and if it is set
              to the string `always', regular aliases will be expanded even if
              not in command position.

       remove-all-dups
              The _history_complete_word bindable command and the _history
              completer use this to decide if all duplicate matches should be
              removed, rather than just consecutive duplicates.

       select-prompt
              If this is set for the default tag, its value will be displayed
              during menu selection (see the menu style above) when the
              completion list does not fit on the screen as a whole.  The same
              escapes as for the list-prompt style are understood, but give
              the number of the match or line the mark is on.  A default
              prompt is used when the value is the empty string.

       select-scroll
              This style is tested for the default tag and determines how a
              completion list is scrolled during a menu selection (see the
              menu style above) when the completion list does not fit on the
              screen as a whole.  Its value should be `0' (zero) to scroll by
              half-screenfuls, a positive integer to scroll by that many lines
              and a negative number to scroll by the number of lines of the
              screen minus that number (or plus the number, since it is
              negative).  The default is to scroll by single lines.

       separate-sections
              This style is used with the manuals tag when completing names of
              manual pages.  If it is `true', entries for different sections
              are added separately using tag names of the form `manual.X',
              where X is the section number.  This means that it is possible
              to make pages from different sections be listed separately by
              setting the group-name style.  The default for this style is
              `false'.

       single-ignored
              This is used by the _ignored completer.  It specifies what
              should be done if it can generate only one match, which is often
              a special case.  If its value is `show', the single match will
              be displayed but not inserted.  If the value is `menu', then the
              single match and the original string are both added as matches
              and menu completion is started so that one can easily select
              either of them.

       sort   If set to `true', completion functions that generate words from
              the history as possible matches sort these words alphabetically
              instead of keeping them in the order in which they appear in the
              history (from youngest to oldest).

              This is also used by the _expand completer.  Here, if it is set
              to `true', the expansions generated will always be sorted.  If
              it is set to `menu', then the expansions are only sorted when
              they are offered as single strings (not in the string containing
              all possible expansions).

       special-dirs
              Normally, the completion code will not produce the directory
              names `.' and `..' as possible completions.  If this style is
              set to `true', it will add both `.' and `..' as possible
              completions; if it is set to `..', only `..' will be added.

       squeeze-slashes
              If set to `true', sequences of slashes (as in `foo//bar') will
              be treated as if they were only one slash when completing
              pathnames.  This is the usual behaviour of UNIX paths.  However,
              by default the file completion function behaves as if there were
              a `*' between the slashes.

       stop   If set to `true', the _history_complete_word bindable command
              will stop once when reaching the beginning or end of the
              history.  Invoking _history_complete_word will then wrap around
              to the opposite end of the history.  If this style is set to
              `false' (the default), _history_complete_word will loop
              immediately as in a menu completion.

       subst-globs-only
              This is used by the _expand completer.  If it is set to `true',
              the expansion will only be used if it resulted from globbing;
              hence, if expansions resulted from the use of the substitute
              style described below, but these were not further changed by
              globbing, the expansions will be rejected.

              The default for this style is `false'.

       substitute
              This boolean style controls whether the _expand completer will
              first try to expand all substitutions in the string (such as
              `$(...)' and `${...}').

              The default is `true'.

       suffix This is used by the _expand completer if the word starts with a
              tilde or contains a parameter expansion. If it is set to `true',
              the word will only be expanded if it doesn't have a suffix, i.e.
              if it is something like `~foo' or `$foo', but not if it is
              `~foo/' or `$foo/bar', unless that suffix itself contains
              characters eligible for expansion.  The default for this style
              is `true'.

       tag-order
              This provides a mechanism for sorting how the tags available in
              a particular context will be used.

              The values for the style are sets of space-separated lists of
              tags.  The tags in each value will be tried at the same time; if
              no match is found, the next value is used.  (See the
              file-patterns style for an exception to this behavior.)

              For example:

                     zstyle ':completion:*:complete:-command-:*' tag-order \
                         'commands functions'

              specifies that completion in command position should offer only
              completions for external commands and shell functions
              immediately.

              In addition to tag names, each string in the value may take one
              of the following forms:

              -      If any string in the value consists of only a hyphen,
                     then only the tags specified by the other strings in the
                     value are generated.  Normally all tags not explicitly
                     selected are tried last if the specified tags fail to
                     generate any matches.  This means that a value consisting
                     only of a single hyphen turns off completion.

              ! tags...
                     A string starting with an exclamation mark specifies
                     names of tags that are not to be used.  The effect is the
                     same as if all other possible tags for the context had
                     been listed.

              tag:label ...
                     In strings not starting with an exclamation mark, it is
                     also possible to specify tag labels instead of only tags,
                     where tag is one of the tags offered by the completion
                     function for the current context and label is a name.
                     For this, the completion function will generate matches
                     in the same way as for the tag but it will use the label
                     in place of the tag in the context names used to look up
                     styles.  If the label starts with a hyphen, the tag is
                     prepended to the label to form the name used for lookup.
                     This can be used to make the completion system try a
                     certain tag more than once, supplying different style
                     settings for each attempt, see below for an example.

                     The label may optionally be followed by a second colon
                     and a description.  This description will then be used
                     for the `%d' in the value of the format style instead of
                     the default description supplied by the completion
                     function.  Spaces in the description have to be quoted by
                     preceding them with a backslash and a `%d' appearing in
                     the description is replaced with the description given by
                     the completion function.

       In each of the cases above, the tag may also be a pattern or more than
       one pattern inside braces and separated by commas.  In this case all of
       the offered tags matching the pattern(s) will be used except for those
       that are given explicitly in the same string.  There are probably two
       main uses of this.  One is the case where one wants to try one of the
       tags more than once, setting other styles differently for each try, but
       still wants to use all the other tags without having to repeat them
       all.  For example, to make completion of function names in command
       position ignore all the completion functions starting with an
       underscore the first time completion is tried, one could do:

              zstyle ':completion:*:*:-command-:*' tag-order \
                  'functions:-non-comp *' functions
              zstyle ':completion:*:functions-non-comp' ignored-patterns '_*'

       Here, the completion system will first try all tags offered, but will
       use the tag label functions-non-comp when looking up styles for the
       function names completed.  For this, the ignored-patterns style is set
       to exclude functions starting with an underscore from the set of
       possible matches.  If none of the generated matches match the string on
       the line, the completion system will use the second value of the
       tag-order style and complete functions names again, but this time using
       the name functions to look up styles, so that the ignored-patterns
       style is not used and all function names are considered.

       Of course, this can also be used to split the matches for one tag into
       different groups. For example:

              zstyle ':completion:*' tag-order \
                  'options:-long:long\ options
                   options:-short:short\ options
                   options:-single-letter:single\ letter\ options'

              zstyle ':completion:*:options-long' ignored-patterns '[-+](|-|[^-]*)'
              zstyle ':completion:*:options-short' ignored-patterns '--*' '[-+]?'
              zstyle ':completion:*:options-single-letter' ignored-patterns '???*'

       With the group-names style set, this makes options beginning with `--',
       options beginning with a single `-' or `+' but containing multiple
       characters, and single-letter options be displayed in separate groups
       with different descriptions.

       The second interesting use of patterns is the case where one wants to
       try multiple match specifications one after another.  The matcher-list
       style offers something similar, but it is tested very early in the
       completion system and hence can't be set for single commands nor for
       more specific contexts.  Here is how to try normal completion without
       any match specification and, if that generates no matches, try again
       with case-insensitive matching, restricting the effect to arguments of
       the command foo:
              zstyle ':completion:*:*:foo:*' tag-order '*' '*:-case'
              zstyle ':completion:*-case' matcher 'm:{a-z}={A-Z}'

       First, all the tags offered when completing after foo are tried using
       the normal tag name.  If that generates no matches, the second value of
       tag-order is used, which tries all tags again except that this time
       each has -case appended to its name for lookup of styles.  Hence this
       time the value for the matcher style from the second call to zstyle in
       the example is used to make completion case-insensitive.

       Using the -e option of the zstyle builtin command, it is possible to
       specify conditions saying when certain tags are to be used. For
       example:

              zstyle -e '*:-command-:*' tag-order '
                  if [[ -n $PREFIX ]]; then
                    reply=( )
                  else
                    reply=( - )
                  fi'

       Makes completion in command position happen only if the string on the
       line is not empty.  This is tested using the PREFIX parameter which is
       special in completion widgets; see zshcompwid for a description of
       these special parameters.  Setting reply to an empty array ensures that
       only the default behaviour of trying all tags at once is used and
       setting it to an array containing only a hyphen disables that default
       behaviour -- thus keeping all tags from being tried.

       If no style has been defined for a context, the strings
       `(|*-)argument-* (|*-)option-* values' and `options' plus all tags
       offered by the completion function will be used to provide a sensible
       default behavior that causes arguments (whether normal command
       arguments or arguments of options) to be completed before option names
       for most commands.

       urls   This is used together with the the urls tag by completion
              functions that generate URLs as possible matches.  If the value
              consists of more than one string or if the only string does not
              name a file or directory, the strings are used as the URLs to
              complete.

              If the value contains only one string and that is the name of a
              normal file, the URLs are taken from that file (where the URLs
              may be separated by white space or newlines).

              Finally, if the only string in the value names a directory, that
              should contain sub-directories named after the retrieval methods
              which occur as the first part of a URL, i.e.  `http', `ftp',
              `bookmark', and so on.  These sub-directories should contain
              files and other sub-directories whose pathnames are possible
              completions after the initial `http://', `ftp://', etc. See the
              description in the file _urls in the User sub-directory of the
              completion system for more information.

       use-cache
              If this is set, the completion caching layer is activated for
              any completions which use it (via the _store_cache,
              _retrieve_cache, and _cache_invalid functions).  The directory
              containing the cache files can be changed with the cache-path
              style.

       use-compctl
              If this style is set to a string not equal to false, 0, no, and
              off, the completion system may use any completion specifications
              defined with the compctl builtin command.  If the style is
              unset, this is done only if the zsh/compctl module is loaded.
              The string may also contain the substring `first' to make the
              definition for `compctl -T' be used, and the substring `default'
              to make the one for `compctl -D' be used.

              Note that this is only intended to smooth the transition from
              compctl to the new completion system and may disappear in the
              future.

              Note also that the definitions from compctl will only be used if
              there is no specific completion function for the command in
              question.  For example, while completing arguments to the
              command foo, if this was handled by a command function _foo,
              compctl would never be tried, while if it was handled by
              _default, compctl would be tried.

       users  This may be set to a list of names that should be completed
              whenever a username is needed. If it is not set or the string on
              the line doesn't match any of the strings in this list, all
              usernames will be completed.

       users-hosts
              The values of this style should be of the form `user@host' or
              `user:host'. It is used for commands that need pairs of user-
              and hostnames.  For such commands, only the pairs from this
              style are used and if, for example, the username is already
              typed, then only the hostnames for which there is a pair with
              that username is defined.

              If set for the my-accounts tag, this is used for commands such
              as rlogin and ssh; in this case the style should contain the
              names of the user's own accounts on remote hosts.  If set for
              the other-accounts tag, it is used for commands such as talk and
              finger and should contain other people's accounts.  Finally, it
              may also be used by some commands with the accounts tag.

       users-hosts-ports
              Like users-hosts but used for commands like telnet and
              containing strings of the form `user@host:port'.

       verbose
              This is used in several contexts to decide if only a simple or a
              verbose list of matches should be generated. For example some
              commands show descriptions for option names if this style is
              `true'.

              The default value for this style is `true'.

       word   This is used by the _list completer, which prevents the
              insertion of completions until a second completion attempt when
              the line has not changed.  The normal way of finding out if the
              line has changed is to compare its entire contents between the
              two occasions.  If this style is true, the comparison is instead
              performed only on the current word.  Hence if completion is
              performed on another word with the same contents, completion
              will not be delayed.

CONTROL FUNCTIONS
       The initialization script compinit redefines all the widgets which
       perform completion to call the supplied widget function _main_complete.
       This function acts as a wrapper calling the so-called `completer'
       functions that generate matches.  If _main_complete is called with
       arguments, these are taken as the names of completer functions to be
       called in the order given.  If no arguments are given, the set of
       functions to try is taken from the completer style.  For example, to
       use normal completion and correction if that doesn't generate any
       matches:

              zstyle ':completion:*' completer _complete _correct

       after calling compinit. The default value for this style is `_complete
       _ignored', i.e. normally only ordinary completion is tried, first with
       the effect of the ignored-patterns style and then without it.  The
       _main_complete function uses the return value of the completer
       functions to decide if other completers should be called.  If the
       return value is zero, no other completers are tried and the
       _main_complete function returns.

       If the first argument to _main_complete is a single hyphen, the
       arguments will not be taken as names of completers. Instead, the second
       argument gives a name to use in the completer field of the context and
       the other arguments give a command name and arguments to call to
       generate the matches.

       The following completer functions are contained in the distribution
       (users may write their own):

       _all_matches
              This completer can be used to add a string consisting of all
              other matches.  To ensure, that this string is always added,
              this completer has to be used as the first completer in the
              list.  The avoid-completer style is used to decide if the string
              should be added.  This will only be done if the matches were
              generated by a completer not named by one of the values of the
              style.

              This function also uses the style old-matches.  If it is set to
              `true' or to the string `only' and there is a list of matches
              from a previous completion, those matches will be inserted in
              the command line.  If it is set to the the string `only', it
              will only insert an old list and won't add the string for all
              matches of the list currently being generated.

              With the old-matches style set, this completer should probably
              not be called unconditionally.  Instead one could use the -e
              option of the zstyle builtin command to add a condition to the
              completer or to the old-matches style.  Alternatively, one could
              use the _generic function to bind _all_matches to a separate key
              binding, for example:

                     zle -C all-matches complete-word _generic
                     bindkey '^Xa' all-matches
                     zstyle ':completion:all-matches::::' old-matches only
                     zstyle ':completion:all-matches:*' completer _all_matches

       _approximate
              This completer function uses the _complete completer to generate
              a list of strings for the context the cursor is currently in,
              allowing you to specify a maximum number of errors:  see the
              description of approximate matching in zshexpn(1) for how errors
              are counted.  The resulting list of corrected and completed
              strings is then presented to the user.  The intended use of this
              completer function is to try after the normal _complete
              completer by setting:

                     zstyle ':completion:*' completer _complete _approximate

              This will give correcting completion if and only if normal
              completion yields no possible completions.  When corrected
              completions are found, the completer will normally start menu
              completion allowing you to cycle through these strings.

              This completer uses the tags corrections and original when
              generating the possible corrections and the original string.
              The format style for the former may contain the additional
              sequences `%e' and `%o' which will be replaced by the number of
              errors accepted to generate the corrections and the original
              string, respectively.

              As with all completers, _approximate uses its name without the
              underscore in the completer field of the context name.  Once it
              has started trying to generate matches, it will append a minus
              sign and the number of errors accepted to its name.
              _approximate will first look for completions with one error,
              then two, and on so up to the limit on the number of errors set
              by the max-errors style.  Hence on the first try the completer
              field of the context contains `approximate-1', on the second try
              `approximate-2', and so on.

              When _approximate is called from another function, the number of
              errors to accept may be given with the -a option.  Its argument
              should be the same as the value of the max-errors style, all in
              one string.

              Note that this completer (and the _correct completer mentioned
              below) can be quite expensive to call, especially when a large
              number of errors are allowed.  One way to avoid this is to set
              up the completer style using the -e option to zstyle so that
              some completers are only used when completion is attempted a
              second time on the same string, e.g.:

                     zstyle ':completion:*' completer '
                       if [[ $_last_try != "$HISTNO$BUFFER$CURSOR" ]]; then
                         _last_try="$HISTNO$BUFFER$CURSOR"
                         reply=(_complete _match _prefix)
                       else
                         reply=(_ignored _correct _approximate)
                       fi'

              This uses the HISTNO parameter and the BUFFER and CURSOR special
              parameters that are available inside zle and completion widgets
              to find out if the command line hasn't changed since the last
              time completion was tried.  Only then are the _ignored, _correct
              and _approximate completers called.

       _complete
              This completer generates all possible completions in a
              context-sensitive manner, i.e. using the settings defined with
              the compdef function explained above and the current settings of
              all special parameters.  This gives the normal completion
              behaviour.

              To complete arguments of commands, _complete uses the utility
              function _normal, which is in turn responsible for finding the
              particular function; it is described below.  Various contexts of
              the form -context-, as mentioned above for the #compdef tag, are
              handled specially.  These are:

              -array-value-
                     for completion on the right hand side of an
                     array-assignment (`foo=(...)').

              -brace-parameter-
                     for completing the name of a parameter expansion within
                     braces (`${...}').

              -command-
                     for completing in a command position.

              -condition-
                     for completion inside conditions (`[[...]]').

              -default-
                     for generating completions when no special completion
                     function is used.

              -equal-
                     for completion of words beginning with an equals sign

              -first-
                     for adding completions before any other completion
                     functions are tried; if this function sets the _compskip
                     parameter to all, no other completion functions will be
                     called, if it is set to a string containing the substring
                     patterns, no pattern completion functions will be called,
                     and if it is set to a string containing default the
                     function for the `-default-' context will not be called,
                     but functions defined for commands will.

              -math- for completion inside mathematical contexts, such as
                     `((...))'.

              -parameter-
                     for completing the name of a parameter expansion
                     (`$...').

              -redirect-
                     for completion after a redirection operator.

              -subscript-
                     for completion inside subscripts.

              -tilde-
                     for completion after a tilde (`~') character, but before
                     a slash.

              -value-
                     for completion on the right hand side of an assignment.

              Default implementations are supplied for each of these contexts,
              in most cases named after the context itself (e.g. completion
              for the `-tilde-' context is done by the function named
              `_tilde').

              Before trying to find a function for a specific context,
              _complete checks if the parameter `compcontext' is set.  If it
              is set to an array, the elements are taken to be the possible
              matches which will be completed using the tag `values' and the
              description `value'.   If it is set to an associative array, the
              keys are used as the possible completions and the values (if
              non-empty) are used as descriptions for the matches.  If
              `compcontext' is set to a string containing colons, it should be
              of the form `tag:descr:action'.  In this case the tag and descr
              give the tag and description to use and the action says what
              should be completed in one of the forms described for the
              _arguments utility function below.

              Finally, if `compcontext' is set to a string without colons, the
              value is taken as the name of the context to use and the
              function defined for that context will be called.  For this
              purpose, there is a special context named -command-line- that
              completes whole command lines (commands and their arguments) and
              is not used by the completion system itself, but has a function
              handling completion for it.

       _correct
              Generate corrections, but not completions, for the current word;
              this is similar to _approximate but will not allow any number of
              extra characters at the cursor as that completer does, hence
              this is similar to spell-checking.  It calls _approximate but
              uses a different completer field in the context name.

              For example, with:

                     zstyle ':completion:::::' completer _complete _correct _approximate
                     zstyle ':completion:*:correct:::' max-errors 2 not-numeric
                     zstyle ':completion:*:approximate:::' max-errors 3 numeric

              correction will accept up to two errors.  If a numeric argument
              is given, correction will not be performed, but correcting
              completion will be, and will accept as many errors as given by
              the numeric argument.  Without a numeric argument, first
              correction and then correcting completion will be tried, with
              the first one accepting two errors and the second one accepting
              three errors.

              When _correct is called as a function, the number of errors to
              accept may be given following the -a option.  The argument
              should be the same as the value of the accept style, all in one
              string.

              This completer function is intended to be used without the
              _approximate completer or, as in the example, just before it.
              Using it after the _approximate completer is useless since
              _approximate will at least generate the corrected strings
              generated by the _correct completer -- and probably more.

       _expand
              This completer function does not really do completion, but
              instead checks if the word on the command line is eligible for
              expansion and, if it is, gives detailed control over how this
              expansion is done.  When using this, one should not use the
              expand-or-complete widget, but instead use complete-word, as
              expand-or-complete will expand the string on the line before the
              completion widget is called.  Also, this completer should be
              called before the _complete completer function.

              The tags used when generating expansions are all-expansions for
              the string containing all possible expansions, expansions when
              adding the possible expansions as single matches and original
              when adding the original string from the line.  In which order
              these strings are generated and which of these strings are
              generated at all can be controlled by using the group-order
              style and by modifying the tag-order style, as usual.

              The format string for all-expansions and for expansions may
              contain the sequence `%o' which will be replaced by the original
              string from the line.

              Which kind of expansion is tried is controlled by the
              substitute, glob and subst-globs-only styles.

              When _expand is called as a function, the different modes may be
              selected with options.  The -s to substitute, -g to glob and -o
              to subst-globs-only.

       _expand_alias
              If the word the cursor is on is an alias, it is expanded and no
              other completers are called.  The types of aliases which are to
              be expanded can be controlled with the regular, global and
              disabled styles.

              This function is also a bindable command, see the section
              `Bindable Commands' below.

       _history
              Complete words from the shell's command  history.  This
              completer uses the remove-all-dups, and sort styles also used by
              the _history_complete_word bindable command, see the section
              `Bindable Commands' below and the section `Completion System
              Configuration' above.

       _ignored
              The ignored-patterns style can be set to a list of patterns
              which are compared against possible completions; matching ones
              are removed.  With this completer those matches can be
              reinstated, as if no ignored-patterns style were set.  The
              completer actually generates its own list of matches; which
              completers are used for this is determined in the same way as
              for the _prefix completer.

              The single-ignored style is used if only one match could be
              generated.  It can be set to show to prevent that match from
              being displayed or inserted into the line, or it can be set to
              menu, in which case the single match and the original string
              from the line will be offered in a menu completion.

       _list  This completer allows one to delay the insertion of matches
              until completion is attempted a second time without the word on
              the line being changed.  On the first attempt, only the list of
              matches will be shown.  It is affected by the styles condition
              and word, see the section `Completion System Configuration'
              above.

       _match This completer is intended to be used after the _complete
              completer. It allows one to give patterns on the command line
              and to complete all strings matching these patterns from the set
              of possible completions for the context the cursor is in,
              without having to set the GLOB_COMPLETE option.

              Normally this will be done by taking the pattern from the line,
              inserting a `*' at the cursor position and comparing the
              resulting pattern with the possible completions generated.
              However, if the match-original style has a value of only, no `*'
              will be inserted.  If match-original has any other non-empty
              string as its value, this completer will first try to generate
              matches without, then with a `*' inserted at the cursor
              position.

              The generated matches will be offered in a menu completion
              unless the insert-unambiguous style is set to `true'.  In this
              case menu completion will only be started if no unambiguous
              string could be generated that is at least as long as the
              original string.  The style may also be set to the string
              `pattern'.  This will keep the pattern on the line intact as
              long as there isn't an unambiguous completion with which it
              could be replaced.

              Note that the matcher specifications defined globally or used by
              the completion functions will not be used.

       _menu  This completer is a simple example function implemented to show
              how menu completion can be done in shell code.  It should be
              used as the first completer and has the effect of making the
              code perform menu completion.  Note that this is independent of
              the setting of the MENU_COMPLETE option and does not work with
              the other menu completion widgets such as reverse-menu-complete,
              or accept-and-menu-complete.

       _oldlist
              This completer controls how the standard completion widgets
              behave when there is an existing list of completions which may
              have been generated by a special completion (i.e. a
              separately-bound completion command).  It allows the ordinary
              completion keys to continue to use the list of completions thus
              generated, instead of producing a new list of ordinary
              contextual completions.  It should appear in the list of
              completers before any of the widgets which generate matches.  It
              uses two styles: old-list and old-menu, see the section
              `Completion System Configuration' above.

       _prefix
              This completer can be used to try completion with the suffix
              (everything after the cursor) ignored.  In other words, the
              suffix will not be considered to be part of the word to complete
              and hence does not need to be matched.  It uses the completer
              style to decide which other completers to call to try to
              generate matches.  If this style is unset, the list of
              completers set for the current context is used -- except, of
              course, the _prefix completer itself.  Furthermore, if this
              completer appears more than once in the list of completers only
              those completers not already tried by the last invocation of
              _prefix will be called.

              For example, consider this global completer style:

                     zstyle ':completion:*' completer \
                         _complete _prefix _correct _prefix:foo

              Here, the _prefix completer tries normal completion but ignoring
              the suffix.  If that doesn't generate any matches, and neither
              does the call to the _correct completer after it, _prefix will
              be called a second time and, now only trying correction with the
              suffix ignored.  If you want to use _prefix as the last resort
              and try only normal completion, you can use:

                     zstyle ':completion:*' completer _complete ... _prefix
                     zstyle ':completion::prefix:*' completer _complete

              The add-space style is also used.  If it is set to `true' then
              _prefix will insert a space between the matches generated (if
              any) and the suffix.

              Note that this completer is only useful if the COMPLETE_IN_WORD
              option is set; otherwise, the cursor will be moved to the end of
              the current word before the completion code is called and hence
              there will be no suffix.

BINDABLE COMMANDS
       In addition to the context-dependent completions provided, which are
       expected to work in an intuitively obvious way, there are a few widgets
       implementing special behaviour which can be bound separately to keys.
       The following is a list of these and their default bindings.

       _bash_completions
              This function is used by two widgets, _bash_complete-word and
              _bash_list-choices.  It exists to provide compatibility with
              completion bindings in bash.  The last character of the binding
              determines what is completed: `!', command names; `$',
              environment variables; `@', host names; `/', file names; `~'
              user names.  In bash, the binding preceded by `\e' gives
              completion, and preceded by `^X' lists options.  As some of
              these bindings clash with standard zsh bindings, only `\e~' and
              `^X~' are bound by default.  To add the rest, the following
              should be added to .zshrc after compinit has been run:

                     for key in '!' '$' '@' '/' '~'; do
                       bindkey "\e$key" _bash_complete-word
                       bindkey "^X$key" _bash_list-choices
                     done

              This includes the bindings for `~' in case they were already
              bound to something else; the completion code does not override
              user bindings.

       _correct_filename (^XC)
              Correct the filename path at the cursor position.  Allows up to
              six errors in the name.  Can also be called with an argument to
              correct a filename path, independently of zle; the correction is
              printed on standard output.

       _correct_word (^Xc)
              Performs correction of the current argument using the usual
              contextual completions as possible choices. This stores the
              string `correct-word' in the function field of the context name
              and then calls the _correct completer.

       _expand_alias (^Xa)
              This function can be used as a completer and as a bindable
              command.  It expands the word the cursor is on if it is an
              alias.  The types of aliases expanded can be controlled with the
              regular, global and disabled styles.

              When used as a bindable command there is one additional feature
              that can be selected by setting the complete style to `true'.
              In this case, if the word isn't the name of an alias,
              _expand_alias tries to complete the word to a full alias name
              without expanding it (but leaving the cursor directly after the
              completed word so that invoking _expand_alias once more will
              expand the now-complete alias name).

       _expand_word (^Xe)
              Performs expansion on the current word:  equivalent to the
              standard expand-word command, but using the _expand completer.
              Before calling it, the function field is set to `expand-word'.

       _generic
              This function is not defined as a widget and not bound by
              default. However, it can be used to define a widget and will
              then store the name of the widget in the function field of the
              context and call the completion system. This allows custom
              completion widgets with their own set of style settings to be
              easily defined. For example, to define a widget that does normal
              completion and starts menu selection, one could do:

                     zle -C foo complete-word _generic
                     bindkey '...' foo
                     zstyle ':completion:foo:*' menu yes select=1

       _history_complete_word (\e/)
              Complete words from the shell's command history. This uses the
              list, remove-all-dups, sort, and stop styles.

       _most_recent_file (^Xm)
              Complete the name of the most recently modified file matching
              the pattern on the command line (which may be blank).  If given
              a numeric argument N, complete the Nth most recently modified
              file.  Note the completion, if any, is always unique.

       _next_tags (^Xn)
              This command alters the set of matches used to that for the next
              tag, or set of tags, either as given by the tag-order style or
              as set by default; these matches would otherwise not be
              available.  Successive invocations of the command cycle through
              all possible sets of tags.

       _read_comp (^X^R)
              Prompt the user for a string, and use that to perform completion
              on the current word.  There are two possibilities for the
              string.  First, it can be a set of words beginning `_', for
              example `_files -/', in which case the function with any
              arguments will be called to generate the completions.
              Unambiguous parts of the function name will be completed
              automatically (normal completion is not available at this point)
              until a space is typed.

              Second, any other string will be passed as a set of arguments to
              compadd and should hence be an expression specifying what should
              be completed.

              A very restricted set of editing commands is available when
              reading the string:  `DEL' and `^H' delete the last character;
              `^U' deletes the line, and `^C' and `^G' abort the function,
              while `RET' accepts the completion.  Note the string is used
              verbatim as a command line, so arguments must be quoted in
              accordance with standard shell rules.

              Once a string has been read, the next call to _read_comp will
              use the existing string instead of reading a new one.  To force
              a new string to be read, call _read_comp with a numeric
              argument.

       _complete_debug (^X?)
              This widget performs ordinary completion, but captures in a
              temporary file a trace of the shell commands executed by the
              completion system.  Each completion attempt gets its own file.
              A command to view each of these files is pushed onto the editor
              buffer stack.

       _complete_help (^Xh)
              This widget displays information about the context names, the
              tags, and the completion functions used when completing at the
              current cursor position. If given a numeric argument other than
              1 (as in `ESC-2 ^Xh'), then the styles used and the contexts for
              which they are used will be shown, too.

              Note that the information about styles may be incomplete; it
              depends on the information available from the completion
              functions called, which in turn is determined by the user's own
              styles and other settings.

       _complete_tag (^Xt)
              This widget completes symbol tags created by the etags or ctags
              programmes (note there is no connection with the completion
              system's tags) stored in a file TAGS, in the format used by
              etags, or tags, in the format created by ctags.  It will look
              back up the path hierarchy for the first occurrence of either
              file; if both exist, the file TAGS is preferred.  You can
              specify the full path to a TAGS or tags file by setting the
              parameter $TAGSFILE or $tagsfile respectively.  The
              corresponding completion tags used are etags and vtags, after
              emacs and vi respectively.

UTILITY FUNCTIONS
       Descriptions follow for utility functions that may be useful when
       writing completion functions.  Most of these reside in the Base
       subdirectory. Like the example functions for commands in the
       distribution, the utility functions generating matches all follow the
       convention of returning zero if they generated completions and non-zero
       if no matching completions could be added.

       When writing completion functions or other ZLE widgets that call
       completion, it might be interesting to know about two more features
       offered by the _main_complete function. The arrays compprefuncs and
       comppostfuncs may be set to contain names of functions that are to be
       called immediately before or after completion has been tried. The
       functions will only be called once, unless they put themselves into the
       arrays again.

       _all_labels [ -12VJ ] tag name descr [ command args ... ]
              This is a convenient interface to the _next_label function
              below, implementing the loop shown in the _next_label example.
              The command is the one that should be called to generate the
              matches. The options stored in the parameter name will
              automatically be inserted into the args given to the command.
              Normally, they are put directly after the command, but if one of
              the args is a single hyphen, they are inserted directly before
              that. If the hyphen is the last argument, that will be removed
              from the argument list before the command is called. This allows
              _all_labels to be used in almost all cases where the matches can
              be generated by a single call to the compadd builtin command or
              by a call to one of the utility functions.

              For example:

                     local expl
                     ...
                     if _requested foo; then
                       ...
                       _all_labels foo expl '...' compadd ... - $matches
                     fi

              Will complete the strings from the matches parameter, using
              compadd with additional options which will take precedence over
              those generated by _all_labels.

       _alternative [ -C name ] specs ...
              This function is useful in simple cases where multiple tags are
              available.  Essentially, it implements a loop like the one
              described for the _tags function above.

              The tags to use and the action to perform if a tag is requested
              are described using the specs which are of the form:
              `tag:descr:action'. The tags are offered using _tags and if the
              tag is requested, the action is executed with the given
              description descr.  The actions supported are those used by the
              _arguments function (described below), without the `->state' and
              `=...' forms.

              For example, the action may be a simple function call. With that
              one could do:

                     _alternative \
                         'users:user:_users' \
                         'hosts:host:_hosts'

              to offer usernames and hostnames as possible matches (which are
              generated by the _users and _hosts functions respectively).

              Note that, like _arguments this will also use _all_labels to
              execute the actions, so one doesn't need to call that explicitly
              unless another tag is to be used, for example in a function
              called from _alternative.

              Like _tags this function supports the -C option to give a
              different name for the argument context field.

       _arguments [ -ACS ] [ -O name ] [ -M matchspec ] spec ...
              This function can be used to complete words on the line by
              describing the options and arguments which may be passed to the
              command for which completion is being performed.  The
              description is given as arguments to this function, with each
              spec describing one option or normal argument of the command.
              The forms of spec understood are:

              n:message:action
              n::message:action
                     This describes the n'th normal argument.  The message
                     will be printed above the matches generated and the
                     action says what can be completed in this position (see
                     below).  If there are two colons before the message, this
                     describes an optional argument.  If the message contains
                     only white space, nothing will be printed above the
                     matches unless the action adds an explanation string
                     itself.

              :message:action
              ::message:action
                     Like the previous one, but describing the next argument.
                     I.e. if you want to describe all arguments a command can
                     get, you can leave out the numbers in the description and
                     just use this form to describe them one after another in
                     the order they have to appear on the line.

              *:message:action
              *::message:action
              *:::message:action
                     This describes how arguments (usually non-option
                     arguments, those not beginning with - or +) are to be
                     completed when no description with one of the first two
                     forms was given. This also means that any number of
                     arguments can be completed.

                     With two colons before the message, the words special
                     array and the CURRENT special parameter are modified to
                     refer only to the normal arguments when the action is
                     executed or evaluated.  With three colons before the
                     message they are modified to refer only to the normal
                     arguments covered by this description.

              optspec[description ...]
                     This describes an option and (if description is given)
                     the arguments that have to come after the option.  If no
                     description is given, this means to offer only the option
                     name as a possible completion in the right places.  (Note
                     that the brackets, above, around description, indicate
                     that zero or more descriptions may appear; but the
                     brackets are not themselves part of this format.  If
                     brackets are used, they are part of the optspec; see
                     below.)

                     In the descriptions below, the option names represented
                     by optname are normally taken to be multi-character
                     names, and a word from the line is considered to contain
                     only one option (or none).  By giving the -s option to
                     _arguments before the first spec, each optname is
                     considered to be a single character and each word from
                     the line may contain more than one such option letter.
                     However, words beginning with two hyphens (like
                     `--prefix') are still considered to contain only one
                     option name.  This allows the use of the `-s' option to
                     describe single-letter options together with such long
                     option names.

                     The -s option may be combined with the option -w to say
                     that more option characters are to be expected even after
                     an option that takes an argument.  For example, if a
                     command takes the options `a' and `b', where `a' takes an
                     argument in the next word, _arguments would normally not
                     complete the other option directly after `-a', but it
                     would allow that if given the -w option.

                     Similarly, the option -W may be given together with -s to
                     force completion of single-letter options even after
                     options that get an argument in the same word.  For
                     example, if a command takes the options `a' and `b',
                     where `a' needs an argument in the same word, directly
                     after the option character, _arguments would normally
                     only execute the action for that argument and not offer
                     other single-letter options as possible completions.  If
                     given the -W option, it will offer other options as
                     possible completions after executing the action for the
                     argument.  Note that, depending on the action, this may
                     mean that the other options can't really be completed,
                     but at least they will be listed.  For more control, use
                     an utility function like _guard in the argument's action.

                     The forms of optspec are:

                     *optspec
                            If the option may be given more than once, a star
                            (`*') must be added in front of one of the
                            following forms of optspec.  Otherwise, if the
                            option is already on the line and to the left of
                            the cursor, it is not offered as a possible
                            completion again.

                     -optname
                     +optname
                            In the simplest form the optspec is just the
                            option name beginning with a minus or a plus sign,
                            such as `-foo'.  The first argument for the option
                            (if any) must follow as a separate word directly
                            after the option.

                            If the command accepts the option with either a
                            leading minus or a leading plus sign, use either
                            `-+optname' or `+-optname' to define both variants
                            at once.

                            In all the following forms, the leading `-' may be
                            replaced or paired with `+' in this way.

                     -optname-
                            The first argument of the option must come
                            directly after the option name in the same word,
                            as in `-foo-:...'.

                     -optname+
                            The first argument may appear immediately after
                            optname in the same word, or may instead appear as
                            a separate word after the option.

                     -optname=
                            The argument may appear as the next word, or in
                            same word as the option name provided that it is
                            separated from it by an equals sign.

                     -optname=-
                            The argument to the option must appear after an
                            equals sign in the same word, and may not be given
                            in the next argument.

                     optspec[explanation]
                            An explanation string may be appended to any of
                            the preceding forms of optspec by enclosing it in
                            brackets, as in `-q[query operation]'.

                            The verbose style is used to decide if these
                            explanation strings should be displayed with the
                            option in a completion listing.

                            If no bracketed explanation string is given but
                            the auto-description style is set and only one
                            argument is described for this optspec, the value
                            of the style is displayed, with any appearance of
                            the sequence `%d' in it replaced by the message of
                            the first description that follows the optspec;
                            see below.

              Note that the special meaning of a leading or trailing - or + in
              optspec means that when the command to be completed accepts
              options like `-+' or `-=', the second character has to be quoted
              with a backslash, as in `-\+'.

              Each description following an optspec must take one of the
              following forms:

              :message:action
              ::message:action
                     Describes a mandatory argument with one colon, or an
                     optional argument with two colons.  As in other forms of
                     spec, the message will be printed above the matches
                     generated (unless it contains only white space, see
                     above) and the action says what can be completed in this
                     position.

              :*pattern:message:action
              :*pattern::message:action
              :*pattern:::message:action
                     This describes multiple arguments.  Only the last
                     description may be given in this form.  If the pattern is
                     empty (i.e., :*:), all following words on the line are to
                     be completed as described by the action; otherwise, all
                     words up to a word matching the pattern are to be
                     completed using the action.

                     When the message is preceded by two colons, the words
                     special array and the CURRENT special parameter are
                     modified during the execution or evaluation of the action
                     to refer only to the words after the option.  When
                     preceded by three colons, they are modified to refer only
                     to the words covered by this description.

                     Note that only one such `:*'-specification is useful and
                     no other argument specification may be given after it.

       To include a colon in any optname, message, or action anywhere above,
       it has to be preceded by a backslash, as `\:'.

       Each of the six forms of spec (yes, there are six, keep track of the
       nestings) may be preceded by a list of option names and argument
       numbers with which the option or argument described is mutually
       exclusive.  This list is given in parentheses, as in `(-two -three
       1)-one:...' or `(-foo):...'.  In the first example, the options `-two'
       and `-three' and the first argument will not be offered as possible
       completions if the option `-one' is on the line before the cursor, and
       in the second example the option `-foo' will not be offered if the
       argument described by the specification is on the line.

       The list may also contain a single star (*) as one of its elements to
       specify that the description for the rest arguments (i.e. a
       specification of the form `*:...') should not be used, a colon (:) to
       specify that the descriptions for all normal (non-option-) arguments
       should not be used and a hyphen (-) to specify that the descriptions
       for all options should not be used.  This paragraph desperately needs
       rewriting.

       To simplify writing writing functions that call _arguments more than
       once, the specs may also start with the character `!' (exclamation
       mark) to make the spec not be completed.  However, if this is used with
       one of the forms describing options, the option (and its arguments, if
       it takes any) will be understood and skipped if they appear on the
       command line.  It's just that the option itself will not be completed.
       This is intended to be used with an array containing the options used
       in the first call to arguments.  The second call can then use
       `\!${^global_options}' to ignore those options and complete only the
       ones understood in the current context.

       In every case above, the action determines how the possible completions
       should be generated.  In places where no sensible matches can be
       generated, the action should consist of only a space. This will make
       the message be displayed but no possible completions listed. Note that
       even in this case the colon at the end of the message is needed. The
       only case where it can be left is when neither a message, nor a action
       is given.

       Except for the `->string' form below, the action will be executed by
       calling the _all_labels function to process all tag labels, so one
       doesn't need to call that explicitly unless another tag is to be used,
       for example in a function called in the action.

       When only one of a fixed set of strings can be completed, the action
       can consist of these strings as a list in parentheses, as in:

              :foo:(foo bar baz)

       Such a list in doubled parentheses should contain strings consisting of
       the string to complete followed by `\:' and a description, as in:

              :foo:((a\:bar b\:baz))

       The matches will be listed together with their descriptions if the
       description style for the values tag is set.

       An action of the form `->string' is used by functions that implement a
       state machine. In this case, the `string's (with all leading and
       trailing spaces and tabs removed) of all actions that have to be used
       will be stored in the global array state.  The function returns with a
       non-zero return value if the cursor is not in a position where options
       can be completed or if the current word could not be completed to an
       option.  But if the -R option is given to _arguments, the function will
       instead return with a return value of 300 (to make it distinguishable
       from other return values) after setting the global `context', `line'
       and `opt_args' parameters as described below, and without resetting any
       changes made to the special parameters such as PREFIX and words.  This
       enables wrapper functions around _arguments to be able to find out if
       they have to make sure that the special completion parameters are not
       reset when they return.

       Note that this means that a function calling _arguments with at least
       one action containing such a `->string' has to declare appropriate
       local parameters as in:

              local context state line
              typeset -A opt_args

       This will ensure that _arguments does not create unused global
       parameters.

       A string in braces is evaluated to generate the matches and if the
       action does not begin with an opening parentheses or brace, it is also
       split into separate words and executed. If the action starts with a
       space, this list of words will be invoked unchanged, otherwise it will
       be invoked with some extra strings placed after the first word which
       can be given as arguments to the compadd builtin command and which make
       sure that the message given in the description will be shown above the
       matches. These arguments are taken from the array parameter `expl'
       which will be set up before executing the action and hence may be used
       in it (normally in an expansion like `$expl[@]').

       If the action starts with `= ' (an equals sign followed by a space),
       _arguments will insert the contents of the argument field of the
       current context as the new first element in the words special array and
       increments the value of the CURRENT special parameter. In other words,
       it inserts a dummy element in the words array and makes CURRENT still
       point to the word in that array where the cursor is. This is only
       really useful when used with one of the forms that make _arguments
       modify the words array to contain only some of the words from the line,
       i.e. one of the argument description forms where the message is
       preceded by two or three colons. For example, when the function called
       in the action for such an argument itself uses _arguments, the dummy
       element is needed to make that second call to _arguments use all words
       from the restricted range for argument parsing. Without the inserted
       dummy element, the first word in the range would be taken (by the
       second _arguments) to be the command name and hence ignored.

       During the evaluation or execution of the action the array `line' will
       be set to the command name and normal arguments from the command line,
       i.e. to the words from the command line excluding all options and their
       arguments. These are stored in the associative array `opt_args', using
       the option names as keys and their arguments as the values. For options
       that have more than one argument these are given as one string,
       separated by colons. All colons in the original arguments are preceded
       with backslashes.

       The parameter `context' (set only in the calling function when using an
       action of the form `->string', not during the evaluation of other
       actions) is set to the automatically created context names. These are
       either strings of the form `option-opt-n' for the n'th argument of the
       option -opt, or strings of the form `argument-n' for the n'th argument
       (for rest arguments the n is the string `rest'). For example, when
       completing the argument of the -o option, the name is `option-o-1' and
       for the second normal (non-option-) argument it is `argument-2'.

       Also, during the evaluation of the action, the context name in the
       curcontext parameter is changed by appending the same string that is
       stored in the context parameter.

       It is also possible to specify multiple sets of options and arguments
       with the sets separated by single hyphens.  The specifications before
       the first hyphen are shared by all sets given after the first hyphen.
       The first word in every other set gives the name of the set. This name
       may appear in exclusion lists in the specifications, either alone or
       before one of the possible values described above (with a `-' between
       the name and the rest).

       For example:

              _arguments \
                  -a \
                - set1 \
                  -c \
                - set2 \
                  -d \
                  ':arg:(x2 y2)'

       This defines two sets. When the command line contains the option `-c',
       the `-d' option and the argument will not be considered possible
       completions. When it contains `-d' or an argument, the option `-c' will
       not be completed any more, but if `-a' is given, both sets will still
       be considered valid, because it appears before the first hyphen, so
       both sets contain this option.

       If the name-string is of the form `(name)' then all specifications in
       the set have an implicit exclusion list containing the name of the set,
       i.e. all specifications are mutual exclusive with all other
       specifications in the same set. This is useful for defining multiple
       sets of options which are mutually exclusive and in which the options
       are aliases for each other. E.g.:

              _arguments \
                  -a -b \
                - '(compress)' \
                  {-c,--compress}'[compress]' \
                - '(uncompress)' \
                  {-d,--decompress}'[decompress]'

       Note that using multiple sets will be slower than using only one set
       because the completion code has to parse the command line once for
       every set. So more than one set should only be used if the command
       syntax is too complicated. Note also that an option specification with
       rest-arguments (as in `-foo:*:...') often allows the use of multiple
       sets to be avoided.

       To simplify the specifications for commands with standard option
       parsing, the options -S and -A may be given.  With -S, no option will
       be completed after a `--' on the line and this argument will otherwise
       be ignored. With -A, no options will be completed after the first
       non-option argument on the line.  The -A has to be followed by a
       pattern matching all strings which are not to be taken as arguments.
       For example, to make _arguments stop completing options after the first
       normal argument, but ignoring all strings starting with a hyphen even
       if they are not described by one of the optspecs, one would use: `-A
       "-*"'.

       Another option supported is `-O name'. The name will be taken as the
       name of an array and its elements will be given to functions called to
       generate matches when executing the actions. For example, this allows
       one to give options for the compadd builtin that should be used for all
       actions.

       Also, the -M option followed by a string may be given before the first
       description. The string will be used as the match specification when
       completing option names and values instead of the default `r:|[_-]=*
       r:|=*'.

       Finally, the option -C can be given to make _arguments modify the
       curcontext parameter when an action of the form `->state' is used. This
       parameter is used to keep track of the current context and in this case
       it (and not the parameter context as explained above) has to be made
       local to make sure that calling functions don't use the modified value.
       Also, the local version of curcontext has to be initialised with the
       old value as in:

              local curcontext="$curcontext"

       The function can also be made to automatically complete long options
       for commands that support the `--help' option as, for example, most of
       the GNU commands do. For this, the string `--' must be given as one
       argument and if it is, the command from the line is invoked with the
       `--help' option and its output is parsed to find possible option names.
       Note that this means that you should be careful to make sure that this
       feature is not used for a command that does not support this option.

       For such automatically found options that get an argument after an `=',
       the function also tries to automatically find out what should be
       completed as the argument.  The possible completions for
       option-arguments can be described with the arguments after the `--'
       (which are not used as described above). Each argument contains one
       description of the form `pattern:message:action'. The message and the
       action have the same format as for the normal option descriptions
       described above. The action will be executed to complete arguments of
       options whose description in the output of the command from the line
       with the `--help' option matches the pattern. For example:

              _arguments -- '*\*:toggle:(yes no)' \
                            '*=FILE*:file:_files' \
                            '*=DIR*:directory:_files -/'

       Here, `yes' and `no' will be completed as the argument of options whose
       description ends in a star, file names for options that contain the
       substring `=FILE' in the description, and paths for options whose
       description contains `=DIR'. In fact, the last two patterns are not
       needed since this function always completes files for option
       descriptions containing `=FILE' and paths for option descriptions that
       contain `=DIR' or `=PATH'. These builtin patterns can be overridden by
       patterns given as arguments, however.

       Note also that _arguments tries to find out automatically if the
       argument for an option is optional. If it fails to automatically detect
       this, the colon before the message can be doubled to tell it about this
       as described for the normal option descriptions above.

       If the pattern ends in `(-)', this will removed from the pattern and
       the action will be used only directly after the `=', not in the next
       word. I.e., this is like a normal specification as described above
       using `=-'.

       The option `-i patterns' (which must be given after the `--') can be
       used to give patterns for options which should not be completed. The
       patterns can be given as the name of an array parameter or as a literal
       list in parentheses. E.g. `-i "(--(en|dis)able-FEATURE*)"' will make
       the options `--enable-FEATURE' and `--disable-FEATURE' be ignored. The
       option `-s pairs' (again, after the `--') can be used to describe
       option aliases. Each pair consists of a pattern and a replacement. E.g.
       some configure-scripts describe options only as `--enable-foo', but
       also accept `--disable-foo'. To allow completion of the second form,
       one would use `-s "(#--enable- --disable-)"'.

       Example:

              _arguments '-l+:left border:' \
                         '-format:paper size:(letter A4)' \
                         '*-copy:output file:_files::resolution:(300 600)' \
                         ':postscript file:_files -g \*.\(ps\|eps\)' \
                         '*:page number:'

       This describes three options: `-l', `-format', and `-copy'. The first
       one gets one argument described as `left border' for which no
       completion will be offered because of the empty action. The argument
       may come directly after the `-l' or it may be given as the next word on
       the line. The `-format' option gets one argument (in the next word)
       described as `paper size' for which only the strings `letter' and `A4'
       will be completed. The `-copy' option differs from the first two in
       that it may appear more than once on the command line and in that it
       accepts two arguments. The first one is mandatory and will be completed
       as a filename. The second one is optional (because of the second colon
       before the description `resolution') and will be completed from the
       strings `300' and `600'.

       The last two descriptions say what should be completed as arguments.
       The first one describes the first argument as a `postscript file' and
       makes files ending in `ps' or `eps' be completed. The last description
       says that all other arguments are `page numbers' but does not give
       possible completions.

       _cache_invalid cache_identifier
              This function returns 0 if the completions cache corresponding
              to the given cache identifier needs rebuilding.  It determines
              this by looking up the cache-policy style for the current
              context, and if it exists, runs the function of the same name,
              supplying the full path to the relevant cache file as the only
              argument.

              Example:

                     _example_caching_policy () {
                         # rebuild if cache is more than a week old
                         oldp=( "$1"(Nmw+1) )
                         (( $#oldp ))
                     }

       _call_function return name [ args ... ]
              If a function name exists, it is called with the arguments args.
              Unless it is the empty string or a single hyphen, return is
              taken as the name of a parameter and the return status from the
              called function is stored in it.  The return value of
              _call_function itself is zero if the function name exists and
              was called and non-zero otherwise.

       _call_program tag string ...
              This function is used in places where a command is called,
              making it possible for the user to override the default command
              call.  It looks up the command style with the supplied tag.  If
              the style is set, its value is used as the command to execute.

              In any case, the strings from the call to _call_program or from
              the style are concatenated with spaces between them and the
              resulting string is evaluated.  The return value is the return
              value of the command called.

       _combination [ -s pattern ] tag style specs ... field opts ...
              This function is used to complete combinations of values such as
              pairs of hostnames and usernames.  The possible values will be
              taken from the style whose name is given as the second argument.
              The first argument is the tag to use to do the lookup.

              The style name should consist of multiple parts separated by
              hyphens which are then used as field names.  Known values for
              such fields can be given after the second argument in arguments
              of the form `field=pattern'.  The first argument without an
              equals sign is taken as the name of the field for which
              completions should be generated.

              The matches generated will be taken from the value of the style.
              These values should contain the possible values for the
              combinations where the values for the different fields are
              separated by colons or characters matching the pattern given
              after the -s option to _combination; normally this is used to
              define character classes like the `-s "[:@]"' used for the
              users-hosts style.

              Only the values for the requested fields for which the patterns
              given in the `field=pattern' match the respective fields in the
              strings from the style value are generated as possible matches.

              If no style with the given name is defined for the given tag but
              a function named with the name of the requested field preceded
              by an underscore is defined, that function will be called to
              generate the matches.  This is also done if none of the strings
              in the value of the style match all the patterns given as
              arguments.

              If the same name is used for more than one field, in both the
              `field=pattern' and the argument that gives the field name to
              complete for, the number of the field (starting with one) may be
              given after the fieldname, separated from it by a colon.

              All arguments after the requested field name are passed to
              compadd when generating matches from the style value, or to the
              functions for the fields if they are called.

       _contexts names ...
              This function looks up the definitions for the context and
              command names given as arguments and calls the handler functions
              for them if there is a definition (given with the compdef
              function).  For example, the function completing inside
              subscripts might use `_contexts -math-' to include the
              completions generated for mathematical environments.

       _describe [ -o ] descr name1 [ name2 ] opts ... -- ...
              This function is useful for preparing a list of command options
              or arguments, together with their descriptions descr, as
              matches.  Multiple groups separated by -- can be supplied,
              potentially with different completion options opts.

              The descr is taken as a string to display above the matches if
              the format style for the descriptions tag is set.  After this
              come one or two names of arrays followed by options to pass to
              compadd.  The first array contains the possible completions with
              their descriptions in the form `completion:description'.  If a
              second array is given, it should have the same number of
              elements as the first one and the corresponding elements are
              added as possible completions instead of the completion strings
              from the first array.  The completion list will retain the
              descriptions from the first array.  Finally, a set of completion
              options can appear.

              If the option `-o' appears before the first argument, the
              matches added will be treated as option names (typically
              following a `-', `--' or `+' on the command line).  This makes
              _describe use the prefix-hidden, prefix-needed and verbose
              styles to find out if the strings should be added at all and if
              the descriptions should be shown.  Without the `-o' option, only
              the verbose style is used.

              _describe uses the _all_labels function to generate the matches,
              so it does not need to appear inside a loop over tag labels.

       _description [ -12VJ ] tag name descr [ specs ... ]
              This function is called before completions are added (typically
              by a call to compadd); it tests various styles and arranges for
              any necessary options to be passed on to compadd.  The styles
              are tested in the current context using the given tag; options
              are put into the array called name for passing on to compadd;
              the description for the current set of matches is passed in
              descr.  The styles tested are: format (which is first tested for
              the given tag and then for the descriptions tag if that isn't
              defined), hidden, matcher, ignored-patterns and group-name (the
              last are tested only for the tag given as the first argument).
              This function also calls the _setup function which tests some
              more styles.

              The string returned by the format style (if any) will be
              modified so that the sequence `%d' is replaced by the descr
              given as the third argument without any leading or trailing
              white space.  If, after removing the white space, the descr is
              the empty string, the format style will not be used and the
              options put into the name array will not contain an explanation
              string to be displayed above the matches.  If _description is
              called with more than three arguments, the additional specs
              should be of the form `char:str' and every appearance of `%char'
              in the format string will be replaced by string.

              The options placed in the array will also make sure that the
              matches are placed in a separate group, depending on the value
              of the group-name style.  Normally a sorted group will be used
              for this (with the `-J' option), but if an option starting with
              `-V', `-J', `-1', or `-2' is given, that option will be included
              in the array, so that it is possible to make the group unsorted
              by giving the option `-V', `-1V', or `-2V'.

              In most cases, the function will be used like this:

                     local expl
                     _description files expl file
                     compadd "$expl[@]" - "$files[@]"

              Note the use of the parameter expl, the hyphen, and the list of
              matches.  Almost all calls to compadd within the completion
              system use a similar format; this ensures that user-specified
              styles are correctly passed down to the builtins which implement
              the internals of completion.

       _files The function _files uses the file-patterns style and calls
              _path_files with all the arguments it was passed except for -g
              and -/.  These two options are used depending on the setting of
              the file-patterns style.

              See _path_files below for a description of the full set of
              options accepted by _files.

       _gnu_generic
              This function is a simple wrapper around the _arguments function
              described above.  It can be used to automatically complete long
              options for commands that understand the `--help' option.  It is
              not intended to be used from completion functions but as a
              top-level completion function in its own right.  For example, to
              enable option completion for the commands foo and bar, one would
              call:

                     compdef _gnu_generic foo bar

              in one of the initialization files after the call to compinit.

              The default installation uses this function only to generate
              completions for some GNU-commands because to complete the
              options, the command has to be called and hence it shouldn't be
              used if one can't be sure that the command understands the
              `--help' option.

       _guard [ options ] pattern [ descr ]
              This function is intended to be used in an action of functions
              like _arguments.  It returns immediately with a non-zero return
              value if the string to be completed does not match the pattern.
              If the pattern matches, the descr is displayed and the function
              returns zero if the word to complete is not empty and non-zero
              otherwise.

              The pattern may be preceded by those options understood by
              compadd that are passed down from _description, namely -M, -J,
              -V, -1, -2, -n, -F and -X.  All of these options, except -X,
              will be ignored.  If the -X option appears, the description
              following it will be used as the string to display if the
              pattern matches, unless the option descr is given to _guard
              itself, which will then take precedence.

              As an example, consider a command taking the options -n and
              -none, where -n has to be followed by a numeric value in the
              same word.  By using either of:

                     _argument '-n-:numeric value:_guard "[0-9]#"' '-none'

              or

                     _argument '-n-: :_guard "[0-9]#" "numeric value"' '-none'

              _arguments can be made to both display the message `numeric
              value' and complete options after `-n<TAB>'.  If the `-n' is
              already followed by one or more digits (matching the pattern
              given to _guard), only the message will be displayed and if the
              `-n' is followed by another character, only options are
              completed.

       _message [ -r ] descr
              The descr is used like the third argument to the _description
              function. However, the resulting string will always be shown
              whether or not matches were generated. This is useful to display
              help texts in places where no completions can be generated
              automatically.

              This function also uses the format style for the messages tag in
              preference to the format style for the descriptions tag. The
              latter is used only if the former is unset.

              If the -r option is given, no style is used and the descr is
              used literally as the string to display. This is only used in
              cases where that string is taken from some pre-processed
              argument list containing an expanded description.

       _multi_parts sep array
              This function receives two arguments: a separator character and
              an array.  As usual, the array may be either the name of an
              array parameter or a literal array in the form `(foo bar)' (i.e.
              a list of words separated by white space in parentheses).  With
              these arguments, this function will complete to strings from the
              array where the parts separated by the separator character are
              completed independently.  For example, the _tar function from
              the distribution caches the pathnames from the tar file in an
              array, and then calls this function to complete these names in
              the way normal filenames are completed by the _path_files
              function, by using `_multi_parts / patharray'.

              If the -i option is present, then any time there is a unique
              match it will immediately be inserted even if that requires
              additional separators to be inserted as well.  When completing
              from a fixed set of possible completions which are really words,
              this is often the expected behaviour; however, if _multi_parts
              should behave like completing pathnames, the -i option should
              not be used.

              Like other utility functions, this function accepts the `-V',
              `-J', `-1', `-2', `-n', `-f', `-X', `-M', `-P', `-S', `-r',
              `-R', and `-q' options and passes them to the compadd builtin.

       _next_label [ -12VJ ] tag name descr [ options ... ]
              This function should be called repeatedly to generate the tag
              labels. On each call it will check if another tag label is to be
              used and, if there is at least one, zero is returned. If no more
              tag labels are to be used, a non-zero status is returned.

              The -12JV options and the first three arguments are given to the
              _description function using the tag label instead of the first
              argument as appropriate. The options given after the descr
              should be other options to be used for compadd or whatever
              function is to be called to add the matches. _next_label will
              store these options in the parameter whose name is given as the
              second argument. This is done in such a way that the description
              given by the user to the tag-order style is preferred over the
              one given to _next_label.

              Note that this function must not be called without a previous
              call to _tags or _requested because it uses the tag label for
              the current tag found by these functions.

              A normal use of this function for the tag labels of the tag foo
              looks like this:

                     local expl ret=1
                     ...
                     if _requested foo; then
                       ...
                       while _next_label foo expl '...'; do
                         compadd "$expl[@]" ... && ret=0
                       done
                       ...
                     fi
                     return ret

       _normal
              This function is used for normal command completion.  It has two
              tasks: completing the first word on the command line as the name
              of a command, and completing the arguments to this command.  In
              the second case, the name of the command is looked up to see if
              special completions exists, including completions defined for
              patterns which match the name.  If none is found, completion is
              performed for the context -default-.

              The function can also be called by other completion functions
              which need to treat a range of words as a command line.  For
              example, the function to complete after the pre-command
              specifiers such as nohup removes the first word from the words
              array, decrements the CURRENT parameter, then calls _normal
              again, with the effect that `nohup cmd ...' is treated the same
              way was `cmd ...'.

              If the command name matches a pattern, the parameter _compskip
              is checked after the call to the corresponding completion
              function.  This has the same effect here as in the -first-
              context: if it is set, no more completion functions are called
              even if there are no matches so far.

       _options
              This can be used to complete option names.  It uses a matching
              specification that ignores a leading `no', ignores underscores
              and allows the user to type upper-case letters which will match
              their lower-case counterparts.  All arguments passed to this
              function are propagated unchanged to the compadd builtin.

       _options_set and _options_unset
              These functions complete only set or unset options, with the
              same matching specification used in the _options function.

              Note that you need to uncomment a few lines in the
              _main_complete function for these functions to work properly.
              The lines in question are used to store the option settings in
              effect before the completion widget locally sets the options it
              needs.  Hence these options are not generally used by the
              completion system.

       _parameters
              This should be used to complete parameter names.  _parameters
              can take a -g pattern option which specifies that only
              parameters whose type matches the pattern should be completed.
              Strings of the same form as those returned by the t parameter
              expansion flag are used here when matching the type.  All other
              arguments are passed unchanged to the compadd builtin.

       _path_files
              The function _path_files is used throughout the completion
              system to complete filenames.  It allows completion of partial
              paths.  For example, the string `/u/i/s/sig' may be completed to
              `/usr/include/sys/signal.h'.

              The options accepted by both _path_files and _files are:

              -f     Complete all filenames.  This is the default.

              -/     Specifies that only directories should be completed.

              -g pattern
                     Specifies that only files matching the pattern should be
                     completed.

              -W paths
                     Specifies path prefixes that are to be prepended to the
                     string from the line to generate the filenames but that
                     should not be inserted in the line or shown in a
                     completion listing.  Here, paths may be the name of an
                     array parameter, a literal list of paths enclosed in
                     parentheses or an absolute pathname.

              -F     This option from the compadd builtin gives direct control
                     over which filenames should be ignored.  If the option is
                     not present, the ignored-patterns style is used.

              These functions also accept the `-J', `-V', `-1', `-2', `-n',
              `-X', `-M', `-P', `-S', `-q', `-r', and `-R' options from the
              compadd builtin.

              Finally, the _path_files function  uses the styles expand,
              ambiguous, special-dirs, list-suffixes and file-sort.

       _regex_arguments name specs ...
              This function is a compiler to generate a completion function.
              The first argument specifies the name of the generated function
              while the remaining arguments specify a completion as a set of
              regular expressions with actions.  The generated function has
              the structure of a finite-state machine whose states correspond
              to the state (i.e. the context) of the completion. This state
              machine uses a command line, which comes from the concatenation
              of the words array up to the current cursor position using null
              characters as separators with no extra quotation.  This is
              analysed and at the end the appropriate action is executed.

              Specification arguments take one of following forms, in which
              metacharacters such as `(', `)', `#' and `|' should be quoted.

              /pattern/ [%lookahead%] [-guard] [:tag:descr:action]
                     This is a primitive element, corresponding to one state
                     of the compiled state machine.  The state is entered if
                     `(#b)((#B)pattern)(#B)lookahead*' matches the command
                     line string.  If it matches, `guard' is evaluated and its
                     return status is examined; if this is successful, the
                     state is entered, otherwise the test fails and other
                     candidates are tried.  The pattern string `[]' is
                     guaranteed never to match.

                     If the test succeeds and the state is entered, the left
                     part of the command line string matched as pattern is
                     removed and the next state is tried, proceeding from
                     inside to outside and from left to right.

                     If no test succeeds and the remaining command line string
                     contains no null character, the completion target is
                     restricted to the remainder of the command line string
                     and actions for the target are executed.  In this case,
                     nothing is actually removed from the command line string
                     so that any previous or neighbouring state may also have
                     actionss.  actionss evaluation are ordered by the
                     tag-order style and specified tag by _alternative.  So,
                     the various formats supported by _alternative can be used
                     in action.  descr is used for setting up the array
                     parameter expl.

              /pattern/+ [%lookahead%] [-guard] [:tag:descr:action]
                     This is similar to `/pattern/ ...' but the left part of
                     the command line string is also considered as part of the
                     completion target.

              /pattern/- [%lookahead%] [-guard] [:tag:descr:action]
                     This is similar to `/pattern/ ...' but the actions of the
                     current and previous states are ignored even if the
                     following state's `pattern' matches the empty string.

              ( spec )
                     This groups specs.

              spec # This allows any number of repetitions of spec.

              spec spec
                     This represents the concatenation of two specs.

              spec | spec
                     Either of the two specs can be matched.

       _requested [ -12VJ ] tag [ name descr [ command args ... ] ]
              This function is called to decide whether a tag already
              registered by a call to _tags (see below) is requested and hence
              completion should be performed for it; it returns status zero if
              the tag is requested and non-zero otherwise.  This will usually
              be done in a loop such as the following:

                     _tags foo bar baz
                     while _tags; do
                       if _requested foo; then
                         ... # perform completion for foo
                       fi
                       ... # test the tags bar and baz in the same way
                       ... # exit loop if matches were generated
                     done

              Note that the test for whether matches were generated is not
              performed until the end of the _tags loop.  This is so that the
              user can specify a set of tags to be tested at the same time in
              the tag-order parameter.

              If the name and the descr are given, _requested calls the
              _description function with these arguments, including the
              options.

              If the command is given, the _all_labels function will be called
              immediately with the same arguments.  This is often useful to do
              both the testing of the tag, getting the description for the
              matches and adding the matches at once.  For example:

                     local expl ret=1
                     _tags foo bar baz
                     while _tags; do
                       _requested foo expl 'description' \
                           compadd foobar foobaz && ret=0
                       ...
                       (( ret )) || break
                     done

              Note that this means that the command has to accept the options
              that have to be passed down to compadd.

       _retrieve_cache cache_identifier
              This function retrieves completion information from the file
              given by cache_identifier, stored in a directory specified by
              the cache-path style (defaults to ~/.zsh/cache).  The return
              value is zero if retrieval was successful.  It will only attempt
              retrieval if the use-cache style is set, so you can call this
              function without worrying about whether the user wanted to use
              the caching layer.

              See _store_cache below for more details.

       _sep_parts
              This function is passed alternating arrays and separators as
              arguments.  The arrays specify completions for parts of strings
              to be separated by the separators.  The arrays may be the names
              of array parameters or a quoted list of words in parentheses.
              For example, with the array `hosts=(ftp news)' the call
              `_sep_parts '(foo bar)' @ hosts' will complete the string  `f'
              to `foo' and the string `b@n' to `bar@news'.

              This function passes the `-V', `-J', `-1', `-2', `-n', `-X',
              `-M', `-P', `-S', `-r', `-R', and `-q' options and their
              arguments to the compadd builtin used to add the matches.

       _setup tag [ group ]
              This function expects a tag as its argument and sets up the
              special parameters used by the completion system appropriately
              for the tag, using styles such as list-colors and last-prompt.

              The optional group gives the name of the group in which the
              matches will be placed. If it is not given, the tag is used as
              the group name.

              Note that this function is called automatically from
              _description so that one normally doesn't have to call it
              explicitly.

       _store_cache cache_identifier vars ...
              This function, when combined with _retrieve_cache and
              _cache_invalid, makes it easy to implement a caching layer for
              your completion functions.  If a completion function needs to
              perform a costly operation in order to generate data which is
              used to calculate completions, you can store that data in
              variables, and use this function to dump the values of those
              variables to a file.  Then, if they are needed in subsequent
              shell invocations, they can be retrieved quickly from that file
              via _retrieve_cache, avoiding the need for repeating the costly
              operation.

              The cache_identifier specifies the file which the data should be
              dumped to, and is stored in a directory specified by the
              cache-path style (defaults to ~/.zsh/cache).  The remaining vars
              arguments are the variables to dump to the file.

              The return value is zero if storage was successful.  The
              function will only attempt storage if the use-cache style is
              set, so you can call this function without worrying about
              whether the user wanted to use the caching layer.

              If your completion function avoids calling _retrieve_cache when
              it already has the completion data in the environment, it should
              probably at least call _cache_invalid to check whether this data
              and the data cached on disk is still valid.

              See the _perl_modules completion function for a simple example
              of usage of this caching layer.

       _tags [ -C name [ tags ... ] ]
              If called with arguments, these are taken as the names of the
              tags for the types of matches the calling completion function
              can generate in the current context.  These tags are stored
              internally and sorted by using the tag-order style.  Following
              calls to this function without arguments from the same function
              will then select the first, second, etc. set of tags requested
              by the user.  To test if a certain tag should be tried, the
              _requested function has to be called (see above).

              The return value is zero if at least one of the tags is
              requested and non-zero otherwise.

              This function also accepts the -C option followed by a name.
              This name is temporarily (i.e. not visible outside _tags) stored
              in the argument field of the context name in the curcontext
              parameter. This allows _tags to be made to use a more specific
              context name without having to change and reset the curcontext
              parameter (which would otherwise have the same effect).

       _values specs ...
              This is used to complete values (strings) and their arguments or
              lists of such values.  It can be used in two ways.

              If the first argument is the option `-O name', this will be used
              in the same way as by the _arguments function, in other words
              the elements of the name array will be given to calls to compadd
              and when executing an action.

              Otherwise, if the first argument (or the first argument after
              the `-O name' option if that is used) is the option `-s', the
              next argument is used as the character that separates multiple
              values.  Thus the values completed appear in the same word on
              the command line, unlike completion using _arguments.

              The first argument (after the options and separator character if
              they are given) is used as a string to print as a description
              before listing the values.

              All other arguments describe the possible values and their
              arguments in the same format used for the description of options
              by the _arguments function (see above).  The only differences
              are that no minus or plus sign is required at the beginning,
              that values can have only one argument and that those forms of
              actions beginning with an equal sign are not supported.

              The character separating a value from its argument can be set
              using the option -S (like -s, followed by the character to use
              as the separator in the next argument).  If this option is not
              used, the equal sign will be used as the separator.

              Example:

                     _values -s , 'description' \
                             '*foo[bar]' \
                             '(two)*one[number]:first count:' \
                             'two[another number]::second count:(1 2 3)'

              This describes three possible values: `foo', `one', and `two'.
              The first is described as `bar', takes no argument and may
              appear more than once.  The second is described as `number', may
              appear more than once, and takes one mandatory argument
              described as `first count' for which no action is specified so
              that it will not be completed automatically.  The `(two)' at the
              beginning says that if the value `one' is on the line, the value
              `two' will not be considered to be a possible completion
              anymore.  Finally, the last value (`two') is described as
              `another number' and takes an optional argument described as
              `second count' which will be completed from the strings `1',
              `2', and `3'. The _values function will complete lists of these
              values separated by commas.

              Like _arguments this function temporarily adds another context
              name component to the current context name while executing the
              action.  Here this name is just the name of the value for which
              the argument is completed.

              To decide if the descriptions for the values (not those for the
              arguments) should be printed, the style verbose is used.

              One last difference from _arguments is that this function uses
              the associative array val_args to report values and their
              arguments, although otherwise this is the same as the opt_args
              association used by _arguments.  This also means that the
              function calling _values should declare the state, line, context
              and val_args parameters as in:

                     local context state line
                     typeset -A val_args

              when using an action of the form `->string'.  With this function
              the context parameter will be set to the name of the value whose
              argument is to be completed.

              Note also that _values normally adds the character used as the
              separator between values as an auto-removable suffix so that
              users don't have to type it themselves.  But when using a
              `->string' action _values can't do that because the matches for
              the argument will be generated by the calling function.  To get
              the usual behaviour, the implementor of the calling function has
              to add the suffix directly by passing the options `-qS x' (where
              x is the separator character specified with the -s option of
              _values) to the function generating the matches or to the
              compadd builtin.

              Like _arguments, _values supports the -C option in which case
              you have to make the parameter curcontext local instead of
              context (as described above).

       _wanted [ -C name ]  [ -12VJ ] tag name descr command args ...
              In many contexts, completion will generate one particular set of
              matches (usually corresponding to a single tag); however, it is
              still necessary to decide whether the user requires matches of
              this type.  This function is useful in such a case.

              Like _requested, it should be passed arguments as for
              _description.  It calls _tags with the given tag and if that
              returns zero (so that the tag is requested by the user) it calls
              _description.  Hence to offer only one tag and immediately use
              the description generated:

                     _wanted tag expl 'description' \
                         compadd matches...

              Unlike _requested, however, _wanted cannot be called without the
              command.  This is because _wanted also implements the loop over
              the tags, not just the one for the labels; conversely, it should
              not be called in the middle of a _tags loop.

              Note that, as for _requested, the command has to accept the
              options that have to be passed down to compadd.

              Like _tags this function supports the -C option to give a
              different name for the argument context field.

COMPLETION DIRECTORIES
       In the source distribution, the files are contained in various
       subdirectories of the Completion directory.  They may have been
       installed in the same structure, or into one single function directory.
       The following is a description of the files found in the original
       directory structure.  If you wish to alter an installed file, you will
       need to copy it to some directory which appears earlier in your fpath
       than the standard directory where it appears.

       Base   The core functions and special completion widgets automatically
              bound to keys.  You will certainly need most of these, though
              will probably not need to alter them.  Many of these are
              documented above.

       Zsh    Functions for completing arguments of shell builtin commands and
              utility functions for this.  Some of these are also used by
              functions from the Unix directory.

       Unix   Functions for completing arguments of external commands and
              suites of commands.  They may need modifying for your system,
              although in many cases some attempt is made to decide which
              version of a command is present.  For example, completion for
              the mount command tries to determine the system it is running
              on, while completion for many other utilities try to decide
              whether the GNU version of the command is in use, and hence
              whether the --help option is supported..

       X, AIX, BSD, ...
              Completion and utility function for commands available only on
              some systems.

zsh 4.0.6                       August 14, 2002                  ZSHCOMPSYS(1)

NAME | DESCRIPTION | INITIALIZATION | COMPLETION SYSTEM CONFIGURATION | CONTROL FUNCTIONS | BINDABLE COMMANDS | UTILITY FUNCTIONS | COMPLETION DIRECTORIES

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