path: root/desktop-entry/desktop-entry-spec.xml

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<article id="index">
  <articleinfo>
    <title>Desktop Entry Specification</title>
    <releaseinfo>Version 1.0</releaseinfo>
	<date>6 Feb 2007</date>
    <authorgroup>
      <author>
	<firstname>Preston</firstname>
	<surname>Brown</surname>
	<affiliation>
	  <address>
	    <email>pbrown@kde.org</email>
	  </address>
	</affiliation>
      </author>
      <author>
	<firstname>Jonathan</firstname>
	<surname>Blandford</surname>
	<affiliation>
	  <address>
	    <email>jrb@redhat.com</email>
	  </address>
	</affiliation>
      </author>
      <author>
	<firstname>Owen</firstname>
	<surname>Taylor</surname>
	<affiliation>
	  <address>
	    <email>otaylor@gtk.org</email>
	  </address>
	</affiliation>
      </author>
      <author>
	<firstname>Vincent</firstname>
	<surname>Untz</surname>
	<affiliation>
	  <address>
	    <email>vuntz@gnome.org</email>
	  </address>
	</affiliation>
      </author>
      <author>
	<firstname>Waldo</firstname>
	<surname>Bastian</surname>
	<affiliation>
	  <address>
	    <email>waldo.bastian@intel.com</email>
	  </address>
	</affiliation>
      </author>
    </authorgroup>
  </articleinfo>

  <sect1 id="introduction">
    <title>Introduction</title>
    <para>
      Both the KDE and GNOME desktop environments have adopted a similar
      format for "desktop entries", or configuration files describing how a
      particular program is to be launched, how it appears in menus, etc.
      It is to the larger community's benefit that a unified standard be
      agreed upon by all parties such that interoperation between the two
      environments, and indeed any additional environments that implement
      the specification, becomes simpler.
    </para>
  </sect1>
  <sect1 id="basic-format">
    <title>Basic format of the file</title>
    <para>
      These desktop entry files should have the extension
      <filename>.desktop</filename>. Determining file type on basis of
      extension makes determining the file type very easy and quick.
      When no file extension is present, the desktop system should
      fall back to recognition via "magic detection".  Desktop entries
      which describe how a directory is to be formatted/displayed
      should be simply called <filename>.directory</filename>.
    </para>
    <para>
      Desktop entry files are encoded as lines of 8-bit characters separated
      by LF characters. Case is significant everywhere in the file.
    </para>
    <para>
      Compliant implementations MUST not remove any fields from the file,
      even if they don't support them.  Such fields must be maintained in a
      list somewhere, and if the file is "rewritten", they will be included.
      This ensures that any desktop-specific extensions will be preserved
      even if another system accesses and changes the file.
    </para>
    <sect2 id="comments">
      <title>Comments</title>
    <para>
      Lines beginning with a <literal>#</literal> and blank lines are
      considered comments and will be ignored, however they should be
      preserved across reads and writes of the desktop entry file.
    </para>
    <para>
      Comment lines are uninterpreted and may contain any character
      (except for LF). However, using UTF-8 for comment lines that
      contain characters not in ASCII is encouraged.
    </para>
    </sect2>
    <sect2 id="group-header">
      <title>Group headers</title>
      <para>
	A group header with name <literal>groupname</literal> is a line in the
	format:
      </para>
      <programlisting>[groupname]</programlisting>
      <para>
	Group names may contain all ASCII characters except for
	<literal>[</literal> and <literal>]</literal> and control characters.
      </para>
      <para>
	Multiple groups may not have the same name.
      </para>
      <para>
	All <literal>{key,value}</literal> pairs following a group header until
	a new group header belong to the group.
      </para>
      <para>
	The basic format of the desktop entry file requires that there be
	a group header named <literal>Desktop Entry</literal>.  There may
	be other groups present in the file, but this is the most
	important group which explicitly needs to be supported.  This
	group should also be used as the "magic key" for automatic MIME
	type detection.  There should be nothing preceding this group in
	the desktop entry file but possibly one or more comments.
      </para>
    </sect2>
    <sect2 id="entries">
      <title>Entries</title>
      <para>
	Entries in the file are <literal>{key,value}</literal> pairs in the
	format:
      </para>
      <programlisting>Key=Value</programlisting>
      <para>
	Space before and after the equals sign should be ignored; the
	<literal>=</literal> sign is the actual delimiter.
      </para>
      <para>
	Key names must contain only the characters
	<literal>A-Za-z0-9-</literal>.
      </para>
      <para>
	As the case is significant, the keys <varname>Name</varname> and
	<varname>NAME</varname> are not equivalent.
      </para>
      <para>
	Multiple keys in the same group may not have the same name. Keys in
	different groups may have the same name.
      </para>
    </sect2>
  </sect1>
  <sect1 id="value-types">
    <title>Possible value types</title>
    <para>
      The value types recognized are <literal>string</literal>,
      <literal>localestring</literal>,
      <literal>boolean</literal>, and
      <literal>numeric</literal>.
    </para>
    <itemizedlist>
      <listitem>
       <para>
	 Values of type <literal>string</literal> may contain all ASCII
	 characters except for control characters.
       </para>
      </listitem>
      <listitem>
       <para>
	 Values of type <literal>localestring</literal> are user displayable,
	 and are encoded in UTF-8.
       </para>
      </listitem>
      <listitem>
       <para>
	  Values of type <literal>boolean</literal> must either be the string
	  <literal>true</literal> or <literal>false</literal>.
       </para>
      </listitem>
      <listitem>
       <para>
	  Values of type <literal>numeric</literal> must be a valid floating
	  point number as recognized by the <literal>%f</literal> specifier for
	  <function>scanf</function>.
       </para>
      </listitem>
    </itemizedlist>
    <para>
      The escape sequences <literal>\s</literal>, <literal>\n</literal>,
      <literal>\t</literal>, <literal>\r</literal>, and
      <literal>\\</literal> are supported for values of type
      <literal>string</literal> and <literal>localestring</literal>, meaning
      ASCII space, newline, tab, carriage return, and backslash, respectively.
    </para>
    <para>
      Some keys can have multiple values. In such a case, the value of the key
      is specified as a plural: for example, <literal>string(s)</literal>. The
      multiple values should be separated by a semicolon, and the value of the
      key should have a semicolon as trailing character. Semicolons in these
      values need to be escaped using <literal>\;</literal>.
    </para>
  </sect1>
  <sect1 id="localized-keys">
    <title>Localized values for keys</title>
    <para>
	  Keys  with type <literal>localestring</literal> may be postfixed by
	  [<replaceable>LOCALE</replaceable>],
	  where <replaceable>LOCALE</replaceable> is the locale type of the
	  entry.  <replaceable>LOCALE</replaceable> must be of the form
	  <literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable>.<replaceable>ENCODING</replaceable>@<replaceable>MODIFIER</replaceable></literal>,
	  where
	  <literal>_<replaceable>COUNTRY</replaceable></literal>,
	  <literal>.<replaceable>ENCODING</replaceable></literal>, 
	  and <literal>@<replaceable>MODIFIER</replaceable></literal>
	  may be omitted. If a postfixed key occurs, the same
	  key must be also present without the postfix.
    </para>
    <para>
      When reading in the desktop entry file, the value of the key is
      selected by matching the current POSIX locale for the
      <varname>LC_MESSAGES</varname> category against the
      <replaceable>LOCALE</replaceable> postfixes of all occurrences
      of the key, with the
      <literal>.<replaceable>ENCODING</replaceable></literal> part
      stripped.
    </para>
    <para>
	  The matching of is done as follows.  If
	  <varname>LC_MESSAGES</varname> is of the form
	  <literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable>.<replaceable>ENCODING</replaceable>@<replaceable>MODIFIER</replaceable></literal>, 
	  then it will match a key of the form
	  <literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable>@<replaceable>MODIFIER</replaceable></literal>. 
	  If such a key does not exist, it will attempt to match
	  <literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable></literal>
	  followed by
	  <literal><replaceable>lang</replaceable>@<replaceable>MODIFIER</replaceable></literal>.
	  Then, a match against <replaceable>lang</replaceable> by itself
	  will be attempted.  Finally, if no matching key is found the
	  required key without a locale specified is used.  The encoding
	  from the <varname>LC_MESSAGES</varname> value is ignored
	  when matching.
    </para>
    <para>
      If <varname>LC_MESSAGES</varname> does not have a <replaceable>MODIFIER</replaceable>
      field, then no key with a modifier will be matched.  Similarly, if
      <varname>LC_MESSAGES</varname> does not have a <replaceable>COUNTRY</replaceable>
      field, then no key with a country specified will be matched.  If
      <varname>LC_MESSAGES</varname> just has a <replaceable>lang</replaceable> field, then
      it will do a straight match to a key with a similar value.  The
      following table lists possible matches of various <varname>LC_MESSAGES</varname> values in
      the order in which they are matched.  Note that the
      <replaceable>ENCODING</replaceable> field isn't shown.
    </para>
    <table>
      <title>Locale Matching</title>
      <tgroup cols="2">
<thead>
  <row>
    <entry><varname>LC_MESSAGES</varname> value</entry>
    <entry>Possible keys in order of matching</entry>
  </row>
</thead>
<tbody>
  <row>
    <entry><literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable>@<replaceable>MODIFIER</replaceable></literal></entry>
    <entry>
      <literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable>@<replaceable>MODIFIER</replaceable></literal>,
      <literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable></literal>,
      <literal><replaceable>lang</replaceable>@<replaceable>MODIFIER</replaceable></literal>,
      <literal><replaceable>lang</replaceable></literal>,
      default value
    </entry>
  </row>
  <row>
    <entry><literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable></literal></entry>
    <entry>
      <literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable></literal>,
      <replaceable>lang</replaceable>,
      default value
    </entry>
  </row>
  <row>
    <entry><literal><replaceable>lang</replaceable>@<replaceable>MODIFIER</replaceable></literal></entry>
    <entry>
      <literal><replaceable>lang</replaceable>@<replaceable>MODIFIER</replaceable></literal>,
      <replaceable>lang</replaceable>,
      default value
    </entry>
  </row>
  <row>
    <entry><replaceable>lang</replaceable></entry>
    <entry>
      <replaceable>lang</replaceable>,
      default value
    </entry>
  </row>
</tbody>
      </tgroup>
    </table>
    
    <para>
      For example, if the current value of the <varname>LC_MESSAGES</varname> category
      is <literal>sr_YU@Latn</literal> and the desktop file includes:
    </para>
    <programlisting>
 Name=Foo
 Name[sr_YU]=...
 Name[sr@Latn]=...
 Name[sr]=...</programlisting>
    <para>
      then the value of the <varname>Name</varname> keyed by <literal>sr_YU</literal> is used.
    </para>
  </sect1>
  <sect1 id="recognized-keys">
    <title>Recognized desktop entry keys</title>
    <para>
      Keys are either OPTIONAL or REQUIRED.  If a key is OPTIONAL it may or
      may not be present in the file.  However, if it isn't, the
      implementation of the standard should not blow up, it must provide
      some sane defaults.
    </para>
    <para>
      Some keys only make sense in the context when another particular key
      is also present.
    </para>
    <para>
      Some example keys: <varname>Name[C]</varname>, <varname>Comment[it]</varname>.
    </para>
    <table>
      <title>Standard Keys</title>
      <tgroup cols="5">
	<thead>
	  <row>
	    <entry>Key</entry>
	    <entry>Description</entry>
	    <entry>Value Type</entry>
	    <entry>REQ?</entry>
	    <entry>Type</entry>
	  </row>
	</thead>
	<tbody>
	  <row>
	    <entry id="key-type"><varname>Type</varname></entry>
	    <entry>
	      This specification defines 3 types of desktop entries:
	      <constant>Application</constant> (type 1),
	      <constant>Link</constant> (type 2)
	      and <constant>Directory</constant> (type 3).
	      To allow the addition of new types in the future, 
	      implementations should ignore desktop entries with an
	      unknown type.
	    </entry>
	    <entry>string</entry>
	    <entry>YES</entry>
	  </row>
	  <row>
	    <entry id="key-version"><varname>Version</varname></entry>
	    <entry>
	      Version of the Desktop Entry Specification that the
	      desktop entry conforms with. Entries that confirm with this 
	      version of the specification should use <literal>1.0</literal>.
	      Note that the version field is not required to be present.
	    </entry>
	    <entry>numeric</entry>
	    <entry>NO</entry>
            <entry>1-3</entry>
	  </row>
	  <row>
	    <entry id="key-name"><varname>Name</varname></entry>
	    <entry>
          Specific name of the application, for example "Mozilla".
	    </entry>
	    <entry>localestring</entry>
	    <entry>YES</entry>
            <entry>1-3</entry>
	  </row>
	  <row>
	    <entry id="key-genericname"><varname>GenericName</varname></entry>
	    <entry>
          Generic name of the application, for example "Web Browser".
	    </entry>
	    <entry>localestring</entry>
	    <entry>NO</entry>
            <entry>1-3</entry>
	  </row>
	  <row>
	    <entry id="key-nodisplay"><varname>NoDisplay</varname></entry>
	    <entry>
		  <varname>NoDisplay</varname> means "this application exists, but don't display it in the menus".
		  This can be useful to e.g. associate this application with MIME types, so that
		  it gets launched from a file manager (or other apps), without having a menu
		  entry for it (there are tons of good reasons for this, including e.g. the
		  <literal>netscape -remote</literal>, or <literal>kfmclient openURL</literal> kind of stuff).
	    </entry>
	    <entry>boolean</entry>
	    <entry>NO</entry>
            <entry>1-3</entry>
	  </row>
	  <row>
	    <entry id="key-comment"><varname>Comment</varname></entry>
	    <entry>
           Tooltip for the entry, for example "View sites on the
           Internet", should not be redundant with <varname>Name</varname> or 
           <varname>GenericName</varname>.
	    </entry>
	    <entry>localestring</entry>
	    <entry>NO</entry>
            <entry>1-3</entry>
	  </row>
	  <row>
	    <entry id="key-icon"><varname>Icon</varname></entry>
	    <entry>
          Icon to display in file manager, menus, etc.  If the
          name is an absolute path, the given file will be
          used. If the name is not an absolute path, the algorithm described
	  in the <ulink
	  url="http://freedesktop.org/wiki/Standards/icon-theme-spec">Icon
	  Theme Specification</ulink> will be used to locate the icon.
	    </entry>
	    <entry>localestring</entry>
	    <entry>NO</entry>
            <entry>1-3</entry>
	  </row>
	  <row>
	    <entry id="key-hidden"><varname>Hidden</varname></entry>
	    <entry>
		  <varname>Hidden</varname> should have been called <varname>Deleted</varname>.
		  It means the user deleted (at his level)
		  something that was present (at an upper level, e.g. in the system dirs). It's
		  strictly equivalent to the <filename>.desktop</filename> file not existing at all, as far as that user is
		  concerned. This can also be used to "uninstall" existing files (e.g. due to a renaming)
		  - by letting <literal>make install</literal> install a file with <literal>Hidden=true</literal> in it.
	    </entry>
	    <entry>boolean</entry>
	    <entry>NO</entry>
            <entry>1-3</entry>
	  </row>
	  <row>
	    <entry id="key-onlyshowin"><varname>OnlyShowIn</varname>, <varname>NotShowIn</varname></entry>
	    <entry>
           A list of strings identifying the environments that should
           display/not display a given desktop entry. Only one of
           these keys, either <varname>OnlyShowIn</varname> or
           <varname>NotShowIn</varname>, may appear in a group (for
           possible values see the <ulink
           url="http://www.freedesktop.org/Standards/menu-spec">Desktop
           Menu Specification</ulink>).
	    </entry>
	    <entry>string(s)</entry>
	    <entry>NO</entry>
            <entry>1-3</entry>
	  </row>
	  <row>
	    <entry id="key-tryexec"><varname>TryExec</varname></entry>
	    <entry>
          File name of a binary on disk used to determine if the
          program is actually installed.  If not, entry may not
          show in menus, etc.
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
            <entry>1</entry>
	  </row>
	  <row>
	    <entry id="key-exec"><varname>Exec</varname></entry>
	    <entry>
           Program to execute, possibly with arguments.
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
            <entry>1</entry>
	  </row>
	  <row>
	    <entry id="key-path"><varname>Path</varname></entry>
	    <entry>
           If entry is of type <constant>Application</constant>, the working directory to run the program in.
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
            <entry>1</entry>
	  </row>
	  <row>
	    <entry id="key-terminal"><varname>Terminal</varname></entry>
	    <entry>
           Whether the program runs in a terminal window.
	    </entry>
	    <entry>boolean</entry>
	    <entry>NO</entry>
            <entry>1</entry>
	  </row>
	  <row>
	    <entry id="key-mimetype"><varname>MimeType</varname></entry>
	    <entry>
           The MIME type(s) supported by this application.
	    </entry>
	    <entry>string(s)</entry>
	    <entry>NO</entry>
            <entry>1</entry>
	  </row>
	  <row>
	    <entry id="key-categories"><varname>Categories</varname></entry>
	    <entry>
          Categories in which the entry should be shown in a menu (for
          possible values see the <ulink
          url="http://www.freedesktop.org/Standards/menu-spec">Desktop
          Menu Specification</ulink>).
	    </entry>
	    <entry>string(s)</entry>
	    <entry>NO</entry>
            <entry>1</entry>
	  </row>
	  <row>
	    <entry id="key-startupnotify"><varname>StartupNotify</varname></entry>
	    <entry>
			If true, it is KNOWN that the application will send a "remove"
			message when started with the DESKTOP_LAUNCH_ID environment variable set.
			If false, it is KNOWN that the application does not work
			with startup notification at all (does not shown any window, breaks
			even when using StartupWMClass, etc.).
			If absent, a reasonable handling is up to implementations (assuming false,
			using StartupWMClass, etc.). (See the <ulink url="http://www.freedesktop.org/Standards/startup-notification-spec">Startup Notification Protocol Specification</ulink> for more details).
	    </entry>
	    <entry>boolean</entry>
	    <entry>NO</entry>
            <entry>1</entry>
	  </row>
	  <row>
	    <entry id="key-startupwmclass"><varname>StartupWMClass</varname></entry>
	    <entry>
			If specified, it is known that the application will map at least one
			window with the given string as its WM class or WM name hint (see the <ulink url="http://www.freedesktop.org/Standards/startup-notification-spec">Startup Notification Protocol Specification</ulink> for more details).
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
            <entry>1</entry>
	  </row>
	  <row>
	    <entry id="key-url"><varname>URL</varname></entry>
	    <entry>
           If entry is Link type, the URL to access.
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
            <entry>2</entry>
	  </row>
	</tbody>
      </tgroup>
    </table>
  </sect1>
  <sect1 id="exec-variables">
    <title>The <varname>Exec</varname> key</title>
    <para>
      The <varname>Exec</varname> key must contain a command line.
      A command line consists of an executable program optionally followed
      by one or more arguments.
      The executable program can either be specified with its full path or
      with the name of the executable only. If no full path is provided the
      executable is looked up in the $PATH used by the desktop environment.   
      The name or path of the executable program may not contain the equal
      sign ("="). Arguments are separated by a space.
    </para>
    <para>
      Arguments may be quoted in whole. If an argument contains a reserved
      character the argument must be quoted. The rules for quoting of
      arguments is also applicable to the executable name or path of the
      executable program as provided.
    </para>
    <para>
      Quoting must be done by enclosing the argument between double quotes
      and escaping the double quote character, backtick character ("`"),
      dollar sign ("$") and backslash character ("\") by preceding it with an
      additional backslash character. Implementations must undo quoting before
      expanding field codes and before passing the argument to the executable
      program. Reserved characters are space (" "), tab, newline, double
      quote, single quote ("'"), backslash character ("\"), 
      greater-than sign ("&gt;"), less-than sign ("&lt;"),
      tilde ("~"), vertical bar ("|"), ampersand ("&amp;"), semicolon (";"),
      dollar sign ("$"), asterisk ("*"), question mark ("?"), hash mark ("#"),
      parenthesis ("(") and (")") and backtick character ("`").
    </para>
    <para>
      Note that the general escape rule for values of type string states that
      the backslash character can be escaped as ("\\") as well and that this
      escape rule is applied before the quoting rule. As such, to
      unambiguously represent a literal backslash character in a quoted
      argument in a desktop entry file requires the use of four successive
      backslash characters ("\\\\"). Likewise, a literal dollar sign in a
      quoted argument in a desktop entry file is unambiguously represented
      with ("\\$").
    </para>
    <para>
      A number of special field codes have been defined which will be
      expanded by the file manager or program launcher when encountered
      in the command line.
      Field codes consist of the percentage character ("%") followed by
      an alpha character. Literal percentage characters must be escaped
      as <literal>%%</literal>.
      Deprecated field codes should be removed from the command line and
      ignored.
      Field codes are expanded only once, the string that is used to
      replace the field code should not be checked for field codes itself.
    </para>
    <para>
      Command lines that contain a field code that is not listed in this
      specification are invalid and must not be processed, in particular
      implementations may not introduce support for field codes not listed
      in this specification. Extensions, if any, should be introduced by
      means of a new key.
    </para>
    <para>
      Implementations must take care not to expand field codes into multiple
      arguments unless explicitly instructed by this specification.
      This means that name fields, filenames and other replacements that
      can contain spaces must be passed as a single argument
      to the executable program after expansion.
    </para>
    <para>
      Although the <varname>Exec</varname> key is defined to have a value
      of the type string, which is limited to ASCII characters, field code
      expansion may introduce non-ASCII characters in arguments.
      Implementations must take care that all characters in arguments
      passed to the executable program are properly encoded according to
      the applicable locale setting.
    </para>
    <para>
    Recognized field codes are as follows:
    </para>
    <informaltable>
      <tgroup cols="2">
	<thead>
	  <row>
	    <entry>Code</entry>
	    <entry>Description</entry>
	  </row>
	</thead>
	<tbody>
	  <row>
	    <entry><literal>%f</literal></entry>
	    <entry>
	      A single file name, even if multiple files are selected.  The system
	      reading the desktop entry should recognize that the program in
	      question cannot handle multiple file arguments, and it should
	      should probably spawn and execute multiple copies of a program
	      for each selected file if the program is not able to handle
	      additional file arguments. If files are not on the local file system
	      (i.e. are on HTTP or FTP locations), the files will be copied to the local
	      file system and <literal>%f</literal> will be expanded to point at the temporary
	      file. Used for programs that do not understand the URL syntax.
	    </entry>
	  </row>
	  <row>
	    <entry><literal>%F</literal></entry>
	    <entry>
	      A list of files. Use for apps that can open several local
	      files at once.
	      Each file is passed as a separate argument to
	      the executable program.
	    </entry>
	  </row>
	  <row>
	    <entry><literal>%u</literal></entry>
	    <entry>
	      A single URL. Local files may either be passed as
	      file: URLs or as file path. 
	    </entry>
	  </row>
	  <row>
	    <entry><literal>%U</literal></entry>
	    <entry>
	      A list of URLs.
	      Each URL is passed as a separate argument to
	      the executable program. Local files may either be passed as
	      file: URLs or as file path. 
	    </entry>
	  </row>
	  <row>
	    <entry><literal>%d</literal></entry>
	    <entry>
	      Deprecated.
	    </entry>
	  </row>
	  <row>
	    <entry><literal>%D</literal></entry>
	    <entry>
	      Deprecated.
	    </entry>
	  </row>
	  <row>
	    <entry><literal>%n</literal></entry>
	    <entry>
	      Deprecated.
	    </entry>
	  </row>
	  <row>
	    <entry><literal>%N</literal></entry>
	    <entry>
	      Deprecated.
	    </entry>
	  </row>
	  <row>
	    <entry><literal>%i</literal></entry>
	    <entry>
              The <varname>Icon</varname> key of the desktop entry
              expanded as two arguments, first
              <literal>--icon</literal> and then the value of the
              <varname>Icon</varname> key. Should not expand to any
              arguments if the <varname>Icon</varname> key is empty
              or missing.
	    </entry>
	  </row>
	  <row>
	    <entry><literal>%c</literal></entry>
	    <entry>
	      The translated name of the application as listed in
	      the appropriate <varname>Name</varname> key in the
	      desktop entry.
	    </entry>
	  </row>
	  <row>
	    <entry><literal>%k</literal></entry>
	    <entry>
	      The location of the desktop file as either a URI (if for
	      example gotten from the vfolder system) or a local
	      filename or empty if no location is known.
	    </entry>
	  </row>
	  <row>
	    <entry><literal>%v</literal></entry>
	    <entry>
	      Deprecated.
	    </entry>
	  </row>
	  <row>
	    <entry><literal>%m</literal></entry>
	    <entry>
	      Deprecated.
	    </entry>
	  </row>
	</tbody>
      </tgroup>
    </informaltable>
    <para>
      A command line may contain at most one %f, %u, %F or %U field code.
      If the application should not open any
      file the %f, %u, %F and %U field codes must be removed from the
      command line and ignored.
    </para>
    <para>
      Field codes must not be used inside a quoted argument, the result of
      field code expansion inside a quoted argument is undefined. The %F and
      %U field codes may only be used as an argument on their own.
    </para>
  </sect1>
  <sect1 id="mime-types">
    <title>Registering MIME Types</title>
    <para>
      The <varname>MimeType</varname> key is used to indicate the MIME
      Types that an application knows how to handle. It is expected that
      for some applications this list could become long.  An application
      is expected to be able to reasonably open files of these types
      using the command listed in the <varname>Exec</varname> key.
    </para>
    <para>
      There should be no priority for MIME Types in this field, or any
      form of priority in the desktop file.  Priority for applications
      is handled external to the <filename>.desktop</filename> files.
    </para>
<!--
    <sect2 id="mime-caching">
      <title>Caching MIME Types</title>
      <para>
	To make parsing of all the desktop files less costly, a
	<command>update-desktop-database</command> program is provided
	that will generate a cache file.  The concept is identical to
	that of the 'update-mime-database' program in that it lets
	applications avoid reading in (potentially) hundreds of files.
	It will need to be run after every desktop file is installed.
	One cache file is created for every directory in
	$XDG_DATA_DIRS/applications/, and will create a file called
	$XDG_DATA_DIRS/applications/mimeinfo.cache.
      </para>
      <para>
	The format of the cache is similar to that of the desktop file,
	and is just a list mapping mime-types to desktop files.  Here's
	a quick example of what it would look like:
      </para>
      <programlisting>application/x-foo=foo.desktop;bar.desktop;
application/x-bar=bar.desktop;</programlisting>
      <para>
	Each MIME Type is listed only once per cache file, and the
	desktop-id is expected to exist in that particular directory.
	That is to say, if the cache file is located at
	<filename>/usr/share/applications/mimeinfo.cache</filename>,
	bar.desktop refers to the file
	<filename>/usr/share/applications/bar.desktop</filename>.
      </para>
    </sect2>
    <sect2 id="mime-priority">
      <title>Priority of MIME Types and desktop files</title>
      <para>
	There is also a preference list to determine preferred
	application of a given MIME Type.  It defines the 'default'
	application to handle a given MIME Type.  It has the same format
	as the cache list.
      </para>
      <programlisting>mime/type=desktop-id.desktop;</programlisting>
      <para>
	If a mime type is listed multiple times (either in the same
	file, or in another file further down the search path), the
	latter mention wins.  If a listed file doesn't exist, or is
	precluded through the <varname>OnlyShowIn</varname> or
	<varname>NotShowIn</varname> keys, they should be ignored.
	This means that applications will have to keep a history of the
	preferred applications that they run into, so that if the top
	desktop file for a given MIME Type isn't available, the second
	one can be tested, etc.
      </para>
      <para>
	It is also worth noting who this mechanism is defined for.  It
	is primarily intended for use by distributors/sysadmins to
	provide a sane set of defaults for their users.  Additionally,
	users themselves can use this mechanism to override the user
	defaults.  We intentionally don't provide a way for application
	authors themselves to list themselves as the default for a given
	type, as we felt that that cannot work.
      </para>
    </sect2>
-->
  </sect1>
  <sect1 id="extending">
    <title>Extending the format</title>
    <para>
      If the standard is to be amended with a new <literal>{key,value}</literal> pair which
      should be applicable to all supporting parties, a group discussion
      will take place.  This is the preferred method for introducing
      changes.  If one particular party wishes to add a field for personal
      use, they should prefix the key with the string <varname>X-<replaceable>PRODUCT</replaceable></varname>,
      e.g. <varname>X-NewDesktop-Foo</varname>, following the precedent set by other IETF and RFC
      standards.
    </para>
    <para>
      Alternatively, fields can be placed in their own group, where they may
      then have arbitrary key names.  If this is the case, the group should
      follow the scheme outlined above,
      i.e. <literal>[X-<replaceable>PRODUCT</replaceable>
      <replaceable>GROUPNAME</replaceable>]</literal> or
      something similar.  These steps will avoid namespace clashes between
      different yet similar environments.
    </para>
  </sect1>
  <appendix id="example">
    <title>Example Desktop Entry File</title>
    <programlisting>
[Desktop Entry]
Version=1.0
Type=Application
Name=Foo Viewer
Comment=The best viewer for Foo objects available!
TryExec=fooview
Exec=fooview %F
Icon=fooview.png
MimeType=image/x-foo;
X-KDE-Library=libfooview
X-KDE-FactoryName=fooviewfactory
X-KDE-ServiceType=FooService</programlisting>
  </appendix>
  <appendix id="kde-items">
  <title>Currently reserved for use within KDE</title>
    <para>
      For historical reasons KDE is using some KDE-specific extensions
      that are currently not prefixed by a <literal>X-KDE-</literal> prefix.
    </para>
    <itemizedlist>
      <listitem>
        <para>
         KDE specific keys: <varname>ServiceTypes</varname>,
         <varname>DocPath</varname>, <varname>Keywords</varname>,
         <varname>InitialPreference</varname>
        </para>
      </listitem>
	  <listitem>
        <para>
         KDE specific types: <constant>ServiceType</constant>,
         <constant>Service</constant> and <constant>FSDevice</constant>
        </para>
      </listitem>
	</itemizedlist>
    <para>
      KDE uses the following additional keys for desktop entries of the
      <constant>FSDevice</constant> type.
    </para>
    <table>	
      <title>FSDevice Specific Keys</title>
      <tgroup cols="3">
	<thead>
	  <row>
	    <entry>Key</entry>
	    <entry>Description</entry>
	    <entry>Value Type</entry>
	  </row>
	</thead>
	<tbody>
	  <row>
	    <entry id="key-dev"><varname>Dev</varname></entry>
	    <entry>
           The device to mount.
	    </entry>
	    <entry>string</entry>
	  </row>
	  <row>
	    <entry id="key-fstype"><varname>FSType</varname></entry>
	    <entry>
           The type of file system to try to mount.
	    </entry>
	    <entry>string</entry>
	  </row>
	  <row>
	    <entry id="key-mountpoint"><varname>MountPoint</varname></entry>
	    <entry>
           The mount point of the device in question.
	    </entry>
	    <entry>string</entry>
	  </row>
	  <row>
	    <entry id="key-readonly"><varname>ReadOnly</varname></entry>
	    <entry>
           Specifies whether or not the device is read only.
	    </entry>
	    <entry>boolean</entry>
	  </row>
	  <row>
	    <entry id="key-unmounticon"><varname>UnmountIcon</varname></entry>
	    <entry>
           Icon to display when device is not mounted.  Mounted devices display icon from the <varname>Icon</varname> key.
		   <varname>UnmountIcon</varname>s may be localized with the <literal>UnmountIcon[xx]=</literal> syntax.
	    </entry>
	    <entry>string</entry>
	  </row>
	</tbody>
      </tgroup>
    </table>
  </appendix>
  <appendix id="deprecated-items">
  <title>Deprecated Items</title>
  <para>
    As this standard is quite old there are some deprecated items that
    may or may not be used by several implementations.
  </para>
    <itemizedlist>
      <listitem>
        <para>
          <literal>Type=MimeType</literal> is deprecated as there is a
          new standard for this now, see the <ulink
          url="http://www.freedesktop.org/Standards/shared-mime-info-spec">Shared
          MIME-info Database specification</ulink> for more
          information. In consequence the Keys
          <varname>Patterns</varname> (various file name extensions
          associated with the MIME type) and
          <varname>DefaultApp</varname> (the default application
          associated with this MIME type) are also deprecated.
        </para>
      </listitem>
      <listitem>
        <para>
          Using <filename>.kdelnk</filename> instead of
          <filename>.desktop</filename> as the file extension is
          deprecated.
        </para>
      </listitem>
      <listitem>
        <para>
          Using <literal>[KDE Desktop Entry]</literal> instead of
          <literal>[Desktop Entry]</literal> as header is deprecated.
        </para>
      </listitem>
      <listitem>
        <para>
	  The <literal>Encoding</literal> key is deprecated. It was used to
	  specify whether keys of type <literal>localestring</literal> were
	  encoded in UTF-8 or in the specified locale. Possible values are
	  <literal>UTF-8</literal> and <literal>Legacy-Mixed</literal>. See
	  <xref linkend="legacy-mixed"/> for more details.
        </para>
      </listitem>
      <listitem>
        <para>
          Deprecated <varname>Exec</varname> field codes:
          <literal>%m</literal> (the mini-icon associated with the
          desktop entry, this should be expanded as two arguments,
          <literal>--miniicon</literal> and the content of the
          <varname>MiniIcon</varname> key, it can also be ignored by
          expanding it to no arguments), %v (the device as listed
          in the <varname>Dev</varname> key in the desktop file),
          %d (the directory of a file), %D (the directories of
          files), %n (the base name of a file) and %N (the base names
          of files).
        </para>
      </listitem>
      <listitem>
        <para>
          Deprecated keys: <varname>MiniIcon</varname> (small icon for
          menus, etc.), <varname>TerminalOptions</varname> (if the
          program runs in a terminal, any options that should be
          passed to the terminal emulator before actually executing
          the program), <varname>Protocols</varname>,
          <varname>Extensions</varname>,
          <varname>BinaryPattern</varname>,
          <varname>MapNotify</varname>.
        </para>
      </listitem>
      <listitem>
        <para>
	  The <literal>SwallowTitle</literal> and
	  <literal>SwallowExec</literal> keys are deprecated.
	  The <literal>SwallowTitle</literal> key is of type
	  <literal>localestring</literal> and specifies the title of the window
	  if is swallowed onto the panel. The <literal>SwallowExec</literal>
	  key is of type <literal>string</literal> and specifies the
	  program to exec if swallowed app is clicked.
        </para>
      </listitem>
      <listitem>
        <para>
	  The <literal>SortOrder</literal> key is deprecated. It is of type
	  <literal>string(s)</literal> and may be used to specify the order in
	  which to display files. The <ulink
          url="http://www.freedesktop.org/Standards/menu-spec">Desktop
          Menu Specification</ulink> defines another mechanism for defining the
	  order of menu items.
        </para>
      </listitem>
      <listitem>
        <para>
	  The <literal>FilePattern</literal> key is deprecated.
	  The value is a list of regular
	  expressions to match against for a file manager to determine if this
	  entry's icon should be displayed. Usually simply the name of the main
	  executable and friends.
        </para>
      </listitem>
      <listitem>
        <para>
    Historically some booleans have been represented by the numeric
    entries <constant>0</constant> or <constant>1</constant>. With
    this version of the standard they are now to be represented as a
    boolean string. However, if an implementation is reading a pre-1.0
    desktop entry, it should interpret <constant>0</constant> and
    <constant>1</constant> as <constant>false</constant> and
    <constant>true</constant>, respectively. 
        </para>
      </listitem>
      <listitem>
        <para>
          Historically lists have been comma separated. This is inconsistent with other lists which are separated by a semicolon. When reading a pre-1.0 desktop entry, comma separated lists should continue to be supported. 
        </para>
      </listitem>
    </itemizedlist>
  </appendix>
  <appendix id="legacy-mixed">
    <title>The <constant>Legacy-Mixed</constant> Encoding (Deprecated)</title>
    <para>
      The <constant>Legacy-Mixed</constant> encoding corresponds to the
      traditional encoding of desktop files in older versions of the GNOME and
      KDE desktop files. In this encoding, the encoding of each
      <literal>localestring</literal> key is determined by the locale tag for
      that key, if any, instead of being UTF-8. For keys without a locale tag,
      the value must contain only ASCII characters.
    </para>
    <para>
      If the file specifies an unsupported encoding, the implementation
      should either ignore the file, or, if the user has requested a direct
      operation on the file (such as opening it for editing), display an
      appropriate error indication to the user.
    </para>
    <para>
      In the absence of an <varname>Encoding</varname> key, the implementation may choose
      to autodetect the encoding of the file by using such factors
      as:
    </para>
    <itemizedlist>
      <listitem>
	<para>
	  The location of the file on the file system
	</para>
      </listitem>
      <listitem>
	<para>
	  Whether the contents of the file are valid UTF-8
	</para>
      </listitem>
    </itemizedlist>
    <para>
      If the implementation does not perform such auto-detection, it should
      treat a file without an <varname>Encoding</varname> key in the same way as a file with an
      unsupported <varname>Encoding</varname> key.
    </para>
    <para>
      If the locale tag includes an <literal>.<replaceable>ENCODING</replaceable></literal> part, then that determines
      the encoding for the line. Otherwise, the encoding is determined
      by the language, or
      <literal><replaceable>lang</replaceable>_<replaceable>COUNTRY</replaceable></literal>
      pair from the locale tag, according to the following table.
    </para>
    <informaltable>
      <tgroup cols="2">
	<thead>
	  <row>
	    <entry>Encoding</entry>
	    <entry>Aliases</entry>
	    <entry>Tags</entry>
	  </row>
	</thead>
	<tbody>
	  <row>
	    <entry>ARMSCII-8 (*)</entry><entry></entry><entry>hy</entry>
	  </row><row>
	    <entry>BIG5</entry><entry></entry><entry>zh_TW</entry>
	  </row><row>
	    <entry>CP1251</entry><entry></entry><entry>be bg</entry>
	  </row><row>
	    <entry>EUC-CN</entry><entry>GB2312</entry><entry>zh_CN</entry>
	  </row><row>
	    <entry>EUC-JP</entry><entry></entry><entry>ja</entry>
	  </row><row>
	    <entry>EUC-KR</entry><entry></entry><entry>ko</entry>
	  </row><row>
	    <entry>GEORGIAN-ACADEMY (*)</entry><entry></entry><entry></entry>
	  </row><row>
	    <entry>GEORGIAN-PS (*)</entry><entry></entry><entry>ka</entry>
	  </row><row>
	    <entry>ISO-8859-1</entry><entry></entry><entry>br ca da de en es eu fi fr gl it nl no pt sv wa</entry>
	  </row><row>
	    <entry>ISO-8859-2</entry><entry></entry><entry>cs hr hu pl ro sk sl sq sr</entry>
	  </row><row>
	    <entry>ISO-8859-3 </entry><entry></entry><entry>eo</entry>
	  </row><row>
	    <entry>ISO-8859-5</entry><entry></entry><entry>mk sp</entry>
	  </row><row>
	    <entry>ISO-8859-7</entry><entry></entry><entry>el</entry>
	  </row><row>
	    <entry>ISO-8859-9</entry><entry></entry><entry>tr</entry>
	  </row><row>
	    <entry>ISO-8859-13</entry><entry></entry><entry>lt lv mi</entry>
	  </row><row>
	    <entry>ISO-8859-14</entry><entry></entry><entry>cy ga</entry>
	  </row><row>
	    <entry>ISO-8859-15</entry><entry></entry><entry>et</entry>
	  </row><row>
	    <entry>KOI8-R</entry><entry></entry><entry>ru</entry>
	  </row><row>
	    <entry>KOI8-U</entry><entry></entry><entry>uk</entry>
	  </row><row>
	    <entry>TCVN-5712 (*)</entry><entry>TCVN</entry><entry>vi</entry>
	  </row><row>
	    <entry>TIS-620</entry><entry></entry><entry>th</entry>
	  </row><row>
	    <entry>VISCII</entry><entry></entry><entry></entry>
	  </row>
	</tbody>
      </tgroup>
    </informaltable>
    <variablelist>
      <varlistentry>
	<term>Encoding</term>
	<listitem>
	  <para>
	    The name given here is listed here is typically the
	    canonical name for the encoding in the GNU C Library's
	    <function>iconv</function> facility.  Encodings marked with (*) are not
	    currently supported by the GNU C Library; for this reason,
	    implementations may choose to ignore lines in desktop
	    files that resolve to this encoding. Desktop files with
	    these encodings are currently rare or non-existent.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>Aliases</term>
	<listitem>
	  <para>
	    Other names for the encoding found in existing desktop
	    files.
	  </para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>Tags</term>
	<listitem>
	  <para>
	    Language tags for which this is the default encoding.
	  </para>
	</listitem>
      </varlistentry>
    </variablelist>
    <para>
      This table above covers all tags and encodings that are known to
      be currently in use. Implementors may choose to support
      encodings not in the above set. For tags without defaults listed
      in the above table, desktop file creators must specify the
      <literal>.<replaceable>ENCODING</replaceable></literal> part of the locale tag.
    </para>
    <para>
      Matching the <literal>.<replaceable>ENCODING</replaceable></literal> part of the locale tag against a locale
      name or alias should be done by stripping all punctuation
      characters from both the tag and the name or alias, converting
      both name and alias to lowercase, and comparing the result.
      This is necessary because, for example, <literal>Big5</literal> is frequently
      found instead of <literal>BIG5</literal> and <literal>georgianacademy</literal> instead of
      <literal>GEORGIAN-ACADEMY</literal>. Desktop files creators should, however, use
      the name as it appears in the "Encoding" column above.
    </para>
  </appendix>
</article>