9.6. In-line Elements

9.6.1. Emphasizing Information

To emphasize a particular word or phrase, use emphasis. This may be presented as italic, or bold, or might be spoken differently with a text-to-speech system.

There is no way to change the presentation of the emphasis within the document, no equivalent of HTML's b and i. If the information being presented is important, then consider presenting it in important rather than emphasis.

Example 9.19. emphasis

Usage:

<para>&os; is without doubt <emphasis>the</emphasis>
  premiere &unix;-like operating system for the Intel
  architecture.</para>

Appearance:

FreeBSD is without doubt the premiere UNIX®-like operating system for the Intel architecture.


9.6.2. Acronyms

Many computer terms are acronyms, words formed from the first letter of each word in a phrase. Acronyms are marked up into acronym elements. It is helpful to the reader when an acronym is defined on the first use, as shown in the example below.

Example 9.20. Acronyms

Usage:

<para>Request For Comments (<acronym>RFC</acronym>) 1149
  defined the use of avian carriers for transmission of
  Internet Protocol (<acronym>IP</acronym>) data.  The
  quantity of <acronym>IP</acronym> data currently
  transmitted in that manner is unknown.</para>

Appearance:

Request For Comments (RFC) 1149 defined the use of avian carriers for transmission of Internet Protocol (IP) data. The quantity of IP data currently transmitted in that manner is unknown.


9.6.3. Quotations

To quote text from another document or source, or to denote a phrase that is used figuratively, use quote. Most of the markup tags available for normal text are also available from within a quote.

Example 9.21. Quotations

Usage:

<para>However, make sure that the search does not go beyond the
  <quote>boundary between local and public administration</quote>,
  as <acronym>RFC</acronym> 1535 calls it.</para>

Appearance:

However, make sure that the search does not go beyond the boundary between local and public administration, as RFC 1535 calls it.


9.6.4. Keys, Mouse Buttons, and Combinations

To refer to a specific key on the keyboard, use keycap. To refer to a mouse button, use mousebutton. And to refer to combinations of key presses or mouse clicks, wrap them all in keycombo.

keycombo has an attribute called action, which may be one of click, double-click, other, press, seq, or simul. The last two values denote whether the keys or buttons should be pressed in sequence, or simultaneously.

The stylesheets automatically add any connecting symbols, such as +, between the key names, when wrapped in keycombo.

Example 9.22. Keys, Mouse Buttons, and Combinations

Usage:

<para>To switch to the second virtual terminal, press
  <keycombo action="simul"><keycap>Alt</keycap>
    <keycap>F1</keycap></keycombo>.</para>

<para>To exit <command>vi</command> without saving changes, type
  <keycombo action="seq"><keycap>Esc</keycap><keycap>:</keycap>
    <keycap>q</keycap><keycap>!</keycap></keycombo>.</para>

<para>My window manager is configured so that
  <keycombo action="simul"><keycap>Alt</keycap>
    <mousebutton>right</mousebutton>
  </keycombo> mouse button is used to move windows.</para>

Appearance:

To switch to the second virtual terminal, press Alt+F1.

To exit vi without saving changes, type Esc : q !.

My window manager is configured so that Alt+right mouse button is used to move windows.


9.6.5. Applications, Commands, Options, and Cites

Both applications and commands are frequently referred to when writing documentation. The distinction between them is that an application is the name of a program or suite of programs that fulfill a particular task. A command is the filename of a program that the user can type and run at a command line.

It is often necessary to show some of the options that a command might take.

Finally, it is often useful to list a command with its manual section number, in the command(number) format so common in Unix manuals.

Mark up application names with application.

To list a command with its manual section number (which should be most of the time) the DocBook element is citerefentry. This will contain a further two elements, refentrytitle and manvolnum. The content of refentrytitle is the name of the command, and the content of manvolnum is the manual page section.

This can be cumbersome to write, and so a series of general entities have been created to make this easier. Each entity takes the form &man.manual-page.manual-section;.

The file that contains these entities is in doc/share/xml/man-refs.ent, and can be referred to using this FPI:

PUBLIC "-//FreeBSD//ENTITIES DocBook Manual Page Entities//EN"

Therefore, the introduction to FreeBSD documentation will usually include this:

<!DOCTYPE book PUBLIC "-//FreeBSD//DTD DocBook V4.1-Based Extension//EN" [

<!ENTITY % man PUBLIC "-//FreeBSD//ENTITIES DocBook Manual Page Entities//EN">
%man;

…

]>

Use command to include a command name in-line but present it as something the user should type.

Use option to mark up the options which will be passed to a command.

When referring to the same command multiple times in close proximity, it is preferred to use the &man.command.section; notation to markup the first reference and use command to markup subsequent references. This makes the generated output, especially HTML, appear visually better.

Example 9.23. Applications, Commands, and Options

Usage:

<para><application>Sendmail</application> is the most
  widely used Unix mail application.<para>

<para><application>Sendmail</application> includes the
  <citerefentry>
    <refentrytitle>sendmail</refentrytitle>
    <manvolnum>8</manvolnum>
  </citerefentry>, &man.mailq.1;, and &man.newaliases.1;
  programs.</para>

<para>One of the command line parameters to <citerefentry>
    <refentrytitle>sendmail</refentrytitle>
    <manvolnum>8</manvolnum>
  </citerefentry>, <option>-bp</option>, will display the current
  status of messages in the mail queue.  Check this on the command
  line by running <command>sendmail -bp</command>.</para>

Appearance:

Sendmail is the most widely used Unix mail application.

Sendmail includes the sendmail(8), mailq(1), and newaliases(1) programs.

One of the command line parameters to sendmail(8), -bp, will display the current status of messages in the mail queue. Check this on the command line by running sendmail -bp.


Note:

Notice how the &man.command.section; notation is easier to follow.

9.6.6. Files, Directories, Extensions, Device Names

To refer to the name of a file, a directory, a file extension, or a device name, use filename. For directory names, set the class attribute to directory.

Example 9.24. filename

Usage:

<para>The source for the Handbook in English is found in
  <filename
    class="directory">/usr/doc/en_US.ISO8859-1/books/handbook/</filename>.
  The main file is called <filename>book.xml</filename>.
  There is also a <filename>Makefile</filename> and a
  number of files with a <filename>.ent</filename> extension.</para>

<para><filename>kbd0</filename> is the first keyboard detected
  by the system, and appears in
  <filename>/dev</filename>.</para>

Appearance:

The source for the Handbook in English is found in /usr/doc/en_US.ISO8859-1/books/handbook/. The main file is called book.xml. There is also a Makefile and a number of files with a .ent extension.

kbd0 is the first keyboard detected by the system, and appears in /dev.


9.6.7. The Name of Ports

FreeBSD Extension:

These elements are part of the FreeBSD extension to DocBook, and do not exist in the original DocBook DTD.

To include the name of a program from the FreeBSD Ports Collection in the document, use the package tag. Since the Ports Collection can be installed in any number of locations, only include the category and the port name; do not include /usr/ports.

By default, package refers to a binary package. To refer to a port that will be built from source, set the role attribute to port.

Example 9.25. package Tag

Usage:

<para>Install the <package>net/wireshark</package> binary
  package to view network traffic.</para>

<para><package role="port">net/wireshark</package> can also be
  built and installed from the Ports Collection.</para>

Appearance:

Install the net/wireshark binary package to view network traffic.

net/wireshark can also be built and installed from the Ports Collection.


9.6.8. Hosts, Domains, IP Addresses, User Names, Group Names, and Other System Items

FreeBSD Extension:

These elements are part of the FreeBSD extension to DocBook, and do not exist in the original DocBook DTD.

Information for system items is marked up with systemitem. The class attribute is used to identify the particular type of information shown.

class="domainname"

The text is a domain name, such as FreeBSD.org or ngo.org.uk. There is no hostname component.

class="etheraddress"

The text is an Ethernet MAC address, expressed as a series of 2 digit hexadecimal numbers separated by colons.

class="fqdomainname"

The text is a Fully Qualified Domain Name, with both hostname and domain name parts.

class="ipaddress"

The text is an IP address, probably expressed as a dotted quad.

class="netmask"

The text is a network mask, which might be expressed as a dotted quad, a hexadecimal string, or as a / followed by a number (CIDR notation).

class="systemname"

With class="systemname" the marked up information is the simple hostname, such as freefall or wcarchive.

class="username"

The text is a username, like root.

class="groupname"

The text is a groupname, like wheel.

Example 9.26. systemitem and Classes

Usage:

<para>The local machine can always be referred to by the
  name <systemitem class="systemname">localhost</systemitem>, which will have the IP
  address <systemitem class="ipaddress">127.0.0.1</systemitem>.</para>

<para>The <systemitem class="domainname">FreeBSD.org</systemitem>
  domain contains a number of different hosts, including
  <systemitem class="fqdomainname">freefall.FreeBSD.org</systemitem> and
  <systemitem class="fqdomainname">bento.FreeBSD.org</systemitem>.</para>

<para>When adding an <acronym>IP</acronym> alias to an
  interface (using <command>ifconfig</command>)
  <emphasis>always</emphasis> use a netmask of
  <systemitem class="netmask">255.255.255.255</systemitem> (which can
  also be expressed as
  <systemitem class="netmask">0xffffffff</systemitem>).</para>

<para>The <acronym>MAC</acronym> address uniquely identifies
  every network card in existence.  A typical
  <acronym>MAC</acronym> address looks like
  <systemitem class="etheraddress">08:00:20:87:ef:d0</systemitem>.</para>

<para>To carry out most system administration functions
  requires logging in as <systemitem class="username">root</systemitem>.</para>

Appearance:

The local machine can always be referred to by the name localhost, which will have the IP address 127.0.0.1.

The FreeBSD.org domain contains a number of different hosts, including freefall.FreeBSD.org and bento.FreeBSD.org.

When adding an IP alias to an interface (using ifconfig) always use a netmask of 255.255.255.255 (which can also be expressed as 0xffffffff).

The MAC address uniquely identifies every network card in existence. A typical MAC address looks like 08:00:20:87:ef:d0.

To carry out most system administration functions requires logging in as root.


9.6.9. Email Addresses

Email addresses are marked up as email elements. In the HTML output format, the wrapped text becomes a hyperlink to the email address. Other output formats that support hyperlinks may also make the email address into a link.

Example 9.27. email with a Hyperlink

Usage:

<para>An email address that does not actually exist, like
  <email>notreal@example.com</email>, can be used as an
  example.</para>

Appearance:

An email address that does not actually exist, like , can be used as an example.


A FreeBSD-specific extension allows setting the role attribute to nolink to prevent the creation of the hyperlink to the email address.

Example 9.28. email Without a Hyperlink

Usage:

<para>Sometimes a link to an email address like
  <email role="nolink">notreal@example.com</email> is not
  desired.</para>

Appearance:

Sometimes a link to an email address like is not desired.


9.6.10. Describing Makefiles

FreeBSD Extension:

These elements are part of the FreeBSD extension to DocBook, and do not exist in the original DocBook DTD.

Two elements exist to describe parts of Makefiles, buildtarget and varname.

buildtarget identifies a build target exported by a Makefile that can be given as a parameter to make. varname identifies a variable that can be set (in the environment, on the command line with make, or within the Makefile) to influence the process.

Example 9.29. buildtarget and varname

Usage:

<para>Two common targets in a <filename>Makefile</filename>
  are <buildtarget>all</buildtarget> and
  <buildtarget>clean</buildtarget>.</para>

<para>Typically, invoking <buildtarget>all</buildtarget> will
  rebuild the application, and invoking
  <buildtarget>clean</buildtarget> will remove the temporary
  files (<filename>.o</filename> for example) created by the
  build process.</para>

<para><buildtarget>clean</buildtarget> may be controlled by a
  number of variables, including <varname>CLOBBER</varname>
  and <varname>RECURSE</varname>.</para>

Appearance:

Two common targets in a Makefile are all and clean.

Typically, invoking all will rebuild the application, and invoking clean will remove the temporary files (.o for example) created by the build process.

clean may be controlled by a number of variables, including CLOBBER and RECURSE.


9.6.11. Literal Text

Literal text, or text which should be entered verbatim, is often needed in documentation. This is text that is excerpted from another file, or which should be copied exactly as shown from the documentation into another file.

Some of the time, programlisting will be sufficient to denote this text. But programlisting is not always appropriate, particularly when you want to include a portion of a file in-line with the rest of the paragraph.

On these occasions, use literal.

Example 9.30. literal

Usage:

<para>The <literal>maxusers 10</literal> line in the kernel
  configuration file determines the size of many system tables, and is
  a rough guide to how many simultaneous logins the system will
  support.</para>

Appearance:

The maxusers 10 line in the kernel configuration file determines the size of many system tables, and is a rough guide to how many simultaneous logins the system will support.


9.6.12. Showing Items That the User Must Fill In

There will often be times when the user is shown what to do, or referred to a file or command line, but cannot simply copy the example provided. Instead, they must supply some information themselves.

replaceable is designed for this eventuality. Use it inside other elements to indicate parts of that element's content that the user must replace.

Example 9.31. replaceable

Usage:

<screen>&prompt.user; <userinput>man <replaceable>command</replaceable></userinput></screen>

Appearance:

% man command

replaceable can be used in many different elements, including literal. This example also shows that replaceable should only be wrapped around the content that the user is meant to provide. The other content should be left alone.

Usage:

<para>The <literal>maxusers <replaceable>n</replaceable></literal>
  line in the kernel configuration file determines the size of many system
  tables, and is a rough guide to how many simultaneous logins the system will
  support.</para>

<para>For a desktop workstation, <literal>32</literal> is a good value
  for <replaceable>n</replaceable>.</para>

Appearance:

The maxusers n line in the kernel configuration file determines the size of many system tables, and is a rough guide to how many simultaneous logins the system will support.

For a desktop workstation, 32 is a good value for n.


9.6.13. Showing GUI Buttons

Buttons presented by a graphical user interface are marked with guibutton. To make the text look more like a graphical button, brackets and non-breaking spaces are added surrounding the text.

Example 9.32. guibutton

Usage:

<para>Edit the file, then click
  <guibutton>[&nbsp;Save&nbsp;]</guibutton> to save the
  changes.</para>

Appearance:

Edit the file, then click [ Save ] to save the changes.


9.6.14. Quoting System Errors

System errors generated by FreeBSD are marked with errorname. This indicates the exact error that appears.

Example 9.33. errorname

Usage:

<screen><errorname>Panic: cannot mount root</errorname></screen>

Appearance:

Panic: cannot mount root

All FreeBSD documents are available for download at http://ftp.FreeBSD.org/pub/FreeBSD/doc/

Questions that are not answered by the documentation may be sent to <freebsd-questions@FreeBSD.org>.
Send questions about this document to <freebsd-doc@FreeBSD.org>.