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PERLPOD(1)	       Perl Programmers	Reference Guide		    PERLPOD(1)

NAME
       perlpod - the Plain Old Documentation format

DESCRIPTION
       Pod is a	simple-to-use markup language used for writing documentation
       for Perl, Perl programs,	and Perl modules.

       Translators are available for converting	Pod to various formats like
       plain text, HTML, man pages, and	more.

       Pod markup consists of three basic kinds	of paragraphs: ordinary,
       verbatim, and command.

   Ordinary Paragraph
       Most paragraphs in your documentation will be ordinary blocks of	text,
       like this one.  You can simply type in your text	without	any markup
       whatsoever, and with just a blank line before and after.	 When it gets
       formatted, it will undergo minimal formatting, like being rewrapped,
       probably	put into a proportionally spaced font, and maybe even
       justified.

       You can use formatting codes in ordinary	paragraphs, for	bold, italic,
       "code-style", hyperlinks, and more.  Such codes are explained in	the
       "Formatting Codes" section, below.

   Verbatim Paragraph
       Verbatim	paragraphs are usually used for	presenting a codeblock or
       other text which	does not require any special parsing or	formatting,
       and which shouldn't be wrapped.

       A verbatim paragraph is distinguished by	having its first character be
       a space or a tab.  (And commonly, all its lines begin with spaces
       and/or tabs.)  It should	be reproduced exactly, with tabs assumed to be
       on 8-column boundaries.	There are no special formatting	codes, so you
       can't italicize or anything like	that.  A \ means \, and	nothing	else.

   Command Paragraph
       A command paragraph is used for special treatment of whole chunks of
       text, usually as	headings or parts of lists.

       All command paragraphs (which are typically only	one line long) start
       with "=", followed by an	identifier, followed by	arbitrary text that
       the command can use however it pleases.	Currently recognized commands
       are

	   =pod
	   =head1 Heading Text
	   =head2 Heading Text
	   =head3 Heading Text
	   =head4 Heading Text
	   =over indentlevel
	   =item stuff
	   =back
	   =begin format
	   =end	format
	   =for	format text...
	   =encoding type
	   =cut

       To explain them each in detail:

       "=head1 Heading Text"
       "=head2 Heading Text"
       "=head3 Heading Text"
       "=head4 Heading Text"
	   Head1 through head4 produce headings, head1 being the highest
	   level.  The text in the rest	of this	paragraph is the content of
	   the heading.	 For example:

	     =head2 Object Attributes

	   The text "Object Attributes"	comprises the heading there.  The text
	   in these heading commands can use formatting	codes, as seen here:

	     =head2 Possible Values for	C<$/>

	   Such	commands are explained in the "Formatting Codes" section,
	   below.

       "=over indentlevel"
       "=item stuff..."
       "=back"
	   Item, over, and back	require	a little more explanation:  "=over"
	   starts a region specifically	for the	generation of a	list using
	   "=item" commands, or	for indenting (groups of) normal paragraphs.
	   At the end of your list, use	"=back"	to end it.  The	indentlevel
	   option to "=over" indicates how far over to indent, generally in
	   ems (where one em is	the width of an	"M" in the document's base
	   font) or roughly comparable units; if there is no indentlevel
	   option, it defaults to four.	 (And some formatters may just ignore
	   whatever indentlevel	you provide.)  In the stuff in "=item
	   stuff...", you may use formatting codes, as seen here:

	     =item Using C<$|> to Control Buffering

	   Such	commands are explained in the "Formatting Codes" section,
	   below.

	   Note	also that there	are some basic rules to	using "=over" ...
	   "=back" regions:

	   o   Don't use "=item"s outside of an	"=over"	... "=back" region.

	   o   The first thing after the "=over" command should	be an "=item",
	       unless there aren't going to be any items at all	in this
	       "=over" ... "=back" region.

	   o   Don't put "=headn" commands inside an "=over" ... "=back"
	       region.

	   o   And perhaps most	importantly, keep the items consistent:	either
	       use "=item *" for all of	them, to produce bullets; or use
	       "=item 1.", "=item 2.", etc., to	produce	numbered lists;	or use
	       "=item foo", "=item bar", etc.--namely, things that look
	       nothing like bullets or numbers.

	       If you start with bullets or numbers, stick with	them, as
	       formatters use the first	"=item"	type to	decide how to format
	       the list.

       "=cut"
	   To end a Pod	block, use a blank line, then a	line beginning with
	   "=cut", and a blank line after it.  This lets Perl (and the Pod
	   formatter) know that	this is	where Perl code	is resuming.  (The
	   blank line before the "=cut"	is not technically necessary, but many
	   older Pod processors	require	it.)

       "=pod"
	   The "=pod" command by itself	doesn't	do much	of anything, but it
	   signals to Perl (and	Pod formatters)	that a Pod block starts	here.
	   A Pod block starts with any command paragraph, so a "=pod" command
	   is usually used just	when you want to start a Pod block with	an
	   ordinary paragraph or a verbatim paragraph.	For example:

	     =item stuff()

	     This function does	stuff.

	     =cut

	     sub stuff {
	       ...
	     }

	     =pod

	     Remember to check its return value, as in:

	       stuff() || die "Couldn't	do stuff!";

	     =cut

       "=begin formatname"
       "=end formatname"
       "=for formatname	text..."
	   For,	begin, and end will let	you have regions of text/code/data
	   that	are not	generally interpreted as normal	Pod text, but are
	   passed directly to particular formatters, or	are otherwise special.
	   A formatter that can	use that format	will use the region, otherwise
	   it will be completely ignored.

	   A command "=begin formatname", some paragraphs, and a command "=end
	   formatname",	mean that the text/data	in between is meant for
	   formatters that understand the special format called	formatname.
	   For example,

	     =begin html

	     <hr> <img src="thang.png">
	     <p> This is a raw HTML paragraph </p>

	     =end html

	   The command "=for formatname	text..."  specifies that the remainder
	   of just this	paragraph (starting right after	formatname) is in that
	   special format.

	     =for html <hr> <img src="thang.png">
	     <p> This is a raw HTML paragraph </p>

	   This	means the same thing as	the above "=begin html"	... "=end
	   html" region.

	   That	is, with "=for", you can have only one paragraph's worth of
	   text	(i.e., the text	in "=foo targetname text..."), but with
	   "=begin targetname" ... "=end targetname", you can have any amount
	   of stuff in between.	 (Note that there still	must be	a blank	line
	   after the "=begin" command and a blank line before the "=end"
	   command.)

	   Here	are some examples of how to use	these:

	     =begin html

	     <br>Figure	1.<br><IMG SRC="figure1.png"><br>

	     =end html

	     =begin text

	       ---------------
	       |  foo	     |
	       |	bar  |
	       ---------------

	     ^^^^ Figure 1. ^^^^

	     =end text

	   Some	format names that formatters currently are known to accept
	   include "roff", "man", "latex", "tex", "text", and "html".  (Some
	   formatters will treat some of these as synonyms.)

	   A format name of "comment" is common	for just making	notes
	   (presumably to yourself) that won't appear in any formatted version
	   of the Pod document:

	     =for comment
	     Make sure that all	the available options are documented!

	   Some	formatnames will require a leading colon (as in	"=for
	   :formatname", or "=begin :formatname" ... "=end :formatname"), to
	   signal that the text	is not raw data, but instead is	Pod text
	   (i.e., possibly containing formatting codes)	that's just not	for
	   normal formatting (e.g., may	not be a normal-use paragraph, but
	   might be for	formatting as a	footnote).

       "=encoding encodingname"
	   This	command	is used	for declaring the encoding of a	document.
	   Most	users won't need this; but if your encoding isn't US-ASCII,
	   then	put a "=encoding encodingname" command very early in the
	   document so that pod	formatters will	know how to decode the
	   document.  For encodingname,	use a name recognized by the
	   Encode::Supported module.  Some pod formatters may try to guess
	   between a Latin-1 or	CP-1252	versus UTF-8 encoding, but they	may
	   guess wrong.	 It's best to be explicit if you use anything besides
	   strict ASCII.  Examples:

	     =encoding latin1

	     =encoding utf8

	     =encoding koi8-r

	     =encoding ShiftJIS

	     =encoding big5

	   "=encoding" affects the whole document, and must occur only once.

       And don't forget, all commands but "=encoding" last up until the	end of
       its paragraph, not its line.  So	in the examples	below, you can see
       that every command needs	the blank line after it, to end	its paragraph.
       (And some older Pod translators may require the "=encoding" line	to
       have a following	blank line as well, even though	it should be legal to
       omit.)

       Some examples of	lists include:

	 =over

	 =item *

	 First item

	 =item *

	 Second	item

	 =back

	 =over

	 =item Foo()

	 Description of	Foo function

	 =item Bar()

	 Description of	Bar function

	 =back

   Formatting Codes
       In ordinary paragraphs and in some command paragraphs, various
       formatting codes	(a.k.a.	"interior sequences") can be used:

       "I<text>" -- italic text
	   Used	for emphasis (""be I<careful!>"") and parameters (""redo
	   I<LABEL>"")

       "B<text>" -- bold text
	   Used	for switches (""perl's B<-n> switch""),	programs (""some
	   systems provide a B<chfn> for that""), emphasis (""be
	   B<careful!>""), and so on (""and that feature is known as
	   B<autovivification>"").

       "C<code>" -- code text
	   Renders code	in a typewriter	font, or gives some other indication
	   that	this represents	program	text (""C<gmtime($^T)>"") or some
	   other form of computerese (""C<drwxr-xr-x>"").

       "L<name>" -- a hyperlink
	   There are various syntaxes, listed below.  In the syntaxes given,
	   "text", "name", and "section" cannot	contain	the characters '/' and
	   '|';	and any	'<' or '>' should be matched.

	   o   "L<name>"

	       Link to a Perl manual page (e.g., "L<Net::Ping>").  Note	that
	       "name" should not contain spaces.  This syntax is also
	       occasionally used for references	to Unix	man pages, as in
	       "L<crontab(5)>".

	   o   "L<name/"sec">" or "L<name/sec>"

	       Link to a section in other manual page.	E.g., "L<perlsyn/"For
	       Loops">"

	   o   "L</"sec">" or "L</sec>"

	       Link to a section in this manual	page.  E.g., "L</"Object
	       Methods">"

	   A section is	started	by the named heading or	item.  For example,
	   "L<perlvar/$.>" or "L<perlvar/"$.">"	both link to the section
	   started by ""=item $."" in perlvar.	And "L<perlsyn/For Loops>" or
	   "L<perlsyn/"For Loops">" both link to the section started by
	   ""=head2 For	Loops""	in perlsyn.

	   To control what text	is used	for display, you use ""L<text|...>"",
	   as in:

	   o   "L<text|name>"

	       Link this text to that manual page.  E.g., "L<Perl Error
	       Messages|perldiag>"

	   o   "L<text|name/"sec">" or "L<text|name/sec>"

	       Link this text to that section in that manual page.  E.g.,
	       "L<postfix "if"|perlsyn/"Statement Modifiers">"

	   o   "L<text|/"sec">"	or "L<text|/sec>" or "L<text|"sec">"

	       Link this text to that section in this manual page.  E.g.,
	       "L<the various attributes|/"Member Data">"

	   Or you can link to a	web page:

	   o   "L<scheme:...>"

	       "L<text|scheme:...>"

	       Links to	an absolute URL.  For example,
	       "L<http://www.perl.org/>" or "L<The Perl	Home
	       Page|http://www.perl.org/>".

       "E<escape>" -- a	character escape
	   Very	similar	to HTML/XML "&foo;" "entity references":

	   o   "E<lt>" -- a literal < (less than)

	   o   "E<gt>" -- a literal > (greater than)

	   o   "E<verbar>" -- a	literal	| (vertical bar)

	   o   "E<sol>"	-- a literal / (solidus)

	       The above four are optional except in other formatting codes,
	       notably "L<...>", and when preceded by a	capital	letter.

	   o   "E<htmlname>"

	       Some non-numeric	HTML entity name, such as "E<eacute>", meaning
	       the same	thing as "&eacute;" in HTML -- i.e., a lowercase e
	       with an acute (/-shaped)	accent.

	   o   "E<number>"

	       The ASCII/Latin-1/Unicode character with	that number.  A
	       leading "0x" means that number is hex, as in "E<0x201E>".  A
	       leading "0" means that number is	octal, as in "E<075>".
	       Otherwise number	is interpreted as being	in decimal, as in
	       "E<181>".

	       Note that older Pod formatters might not	recognize octal	or hex
	       numeric escapes,	and that many formatters cannot	reliably
	       render characters above 255.  (Some formatters may even have to
	       use compromised renderings of Latin-1/CP-1252 characters, like
	       rendering "E<eacute>" as	just a plain "e".)

       "F<filename>" --	used for filenames
	   Typically displayed in italics.  Example: ""F<.cshrc>""

       "S<text>" -- text contains non-breaking spaces
	   This	means that the words in	text should not	be broken across
	   lines.  Example: "S<$x ? $y : $z>".

       "X<topic	name>" -- an index entry
	   This	is ignored by most formatters, but some	may use	it for
	   building indexes.  It always	renders	as empty-string.  Example:
	   "X<absolutizing relative URLs>"

       "Z<>" --	a null (zero-effect) formatting	code
	   This	is rarely used.	 It's one way to get around using an E<...>
	   code	sometimes.  For	example, instead of ""NE<lt>3""	(for "N<3")
	   you could write ""NZ<><3"" (the "Z<>" breaks	up the "N" and the "<"
	   so they can't be considered the part	of a (fictitious) "N<...>"
	   code).

       Most of the time, you will need only a single set of angle brackets to
       delimit the beginning and end of	formatting codes.  However, sometimes
       you will	want to	put a real right angle bracket (a greater-than sign,
       '>') inside of a	formatting code.  This is particularly common when
       using a formatting code to provide a different font-type	for a snippet
       of code.	 As with all things in Perl, there is more than	one way	to do
       it.  One	way is to simply escape	the closing bracket using an "E" code:

	   C<$a	E<lt>=E<gt> $b>

       This will produce: ""$a <=> $b""

       A more readable,	and perhaps more "plain" way is	to use an alternate
       set of delimiters that doesn't require a	single ">" to be escaped.
       Doubled angle brackets ("<<" and	">>") may be used if and only if there
       is whitespace right after the opening delimiter and whitespace right
       before the closing delimiter!  For example, the following will do the
       trick:

	   C<< $a <=> $b >>

       In fact,	you can	use as many repeated angle-brackets as you like	so
       long as you have	the same number	of them	in the opening and closing
       delimiters, and make sure that whitespace immediately follows the last
       '<' of the opening delimiter, and immediately precedes the first	'>' of
       the closing delimiter.  (The whitespace is ignored.)  So	the following
       will also work:

	   C<<<	$a <=> $b >>>
	   C<<<<  $a <=> $b	>>>>

       And they	all mean exactly the same as this:

	   C<$a	E<lt>=E<gt> $b>

       The multiple-bracket form does not affect the interpretation of the
       contents	of the formatting code,	only how it must end.  That means that
       the examples above are also exactly the same as this:

	   C<< $a E<lt>=E<gt> $b >>

       As a further example, this means	that if	you wanted to put these	bits
       of code in "C" (code) style:

	   open(X, ">>thing.dat") || die $!
	   $foo->bar();

       you could do it like so:

	   C<<<	open(X,	">>thing.dat") || die $! >>>
	   C<< $foo->bar(); >>

       which is	presumably easier to read than the old way:

	   C<open(X, "E<gt>E<gt>thing.dat") || die $!>
	   C<$foo-E<gt>bar();>

       This is currently supported by pod2text (Pod::Text), pod2man
       (Pod::Man), and any other pod2xxx or Pod::Xxxx translators that use
       Pod::Parser 1.093 or later, or Pod::Tree	1.02 or	later.

   The Intent
       The intent is simplicity	of use,	not power of expression.  Paragraphs
       look like paragraphs (block format), so that they stand out visually,
       and so that I could run them through "fmt" easily to reformat them
       (that's F7 in my	version	of vi, or Esc Q	in my version of emacs).  I
       wanted the translator to	always leave the "'" and "`" and """ quotes
       alone, in verbatim mode,	so I could slurp in a working program, shift
       it over four spaces, and	have it	print out, er, verbatim.  And
       presumably in a monospace font.

       The Pod format is not necessarily sufficient for	writing	a book.	 Pod
       is just meant to	be an idiot-proof common source	for nroff, HTML, TeX,
       and other markup	languages, as used for online documentation.
       Translators exist for pod2text, pod2html, pod2man (that's for nroff(1)
       and troff(1)), pod2latex, and pod2fm.  Various others are available in
       CPAN.

   Embedding Pods in Perl Modules
       You can embed Pod documentation in your Perl modules and	scripts.
       Start your documentation	with an	empty line, a "=head1" command at the
       beginning, and end it with a "=cut" command and an empty	line.  The
       perl executable will ignore the Pod text.  You can place	a Pod
       statement where perl expects the	beginning of a new statement, but not
       within a	statement, as that would result	in an error.  See any of the
       supplied	library	modules	for examples.

       If you're going to put your Pod at the end of the file, and you're
       using an	"__END__" or "__DATA__"	cut mark, make sure to put an empty
       line there before the first Pod command.

	 __END__

	 =head1	NAME

	 Time::Local - efficiently compute time	from local and GMT time

       Without that empty line before the "=head1", many translators wouldn't
       have recognized the "=head1" as starting	a Pod block.

   Hints for Writing Pod
       o

	   The podchecker command is provided for checking Pod syntax for
	   errors and warnings.	 For example, it checks	for completely blank
	   lines in Pod	blocks and for unknown commands	and formatting codes.
	   You should still also pass your document through one	or more
	   translators and proofread the result, or print out the result and
	   proofread that.  Some of the	problems found may be bugs in the
	   translators,	which you may or may not wish to work around.

       o   If you're more familiar with	writing	in HTML	than with writing in
	   Pod,	you can	try your hand at writing documentation in simple HTML,
	   and converting it to	Pod with the experimental Pod::HTML2Pod
	   module, (available in CPAN),	and looking at the resulting code.
	   The experimental Pod::PXML module in	CPAN might also	be useful.

       o   Many	older Pod translators require the lines	before every Pod
	   command and after every Pod command (including "=cut"!) to be a
	   blank line.	Having something like this:

	    # -	- - - -	- - - -	- - -
	    =item $firecracker->boom()

	    This noisily detonates the firecracker object.
	    =cut
	    sub	boom {
	    ...

	   ...will make	such Pod translators completely	fail to	see the	Pod
	   block at all.

	   Instead, have it like this:

	    # -	- - - -	- - - -	- - -

	    =item $firecracker->boom()

	    This noisily detonates the firecracker object.

	    =cut

	    sub	boom {
	    ...

       o   Some	older Pod translators require paragraphs (including command
	   paragraphs like "=head2 Functions") to be separated by completely
	   empty lines.	 If you	have an	apparently empty line with some	spaces
	   on it, this might not count as a separator for those	translators,
	   and that could cause	odd formatting.

       o   Older translators might add wording around an L<> link, so that
	   "L<Foo::Bar>" may become "the Foo::Bar manpage", for	example.  So
	   you shouldn't write things like "the	L<foo> documentation", if you
	   want	the translated document	to read	sensibly.  Instead, write "the
	   L<Foo::Bar|Foo::Bar>	documentation" or "L<the Foo::Bar
	   documentation|Foo::Bar>", to	control	how the	link comes out.

       o   Going past the 70th column in a verbatim block might	be
	   ungracefully	wrapped	by some	formatters.

SEE ALSO
       perlpodspec, "PODs: Embedded Documentation" in perlsyn, perlnewmod,
       perldoc,	pod2html, pod2man, podchecker.

AUTHOR
       Larry Wall, Sean	M. Burke

perl v5.26.0			  2017-04-19			    PERLPOD(1)

NAME | DESCRIPTION | SEE ALSO | AUTHOR

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