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

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<article id="index">
  <artheader>
    <title>Desktop Entry Standard</title>
    <releaseinfo>Version 0.9.3</releaseinfo>
    <date>13 March 2001</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>
    </authorgroup>
  </artheader>

  <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 an extension of ".desktop" or
      ".kdelnk".  ".kdelnk" is deprecated, and is only maintained for
      backwards compatibility.  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
      ".directory".
    </para>
    <para>
      The basic format of the desktop entry file requires that there be a
      "group" header named "[Desktop Entry]".  For backwards compatibility,
      implementations may also support the header "[KDE Desktop Entry]".
      This "group" entry denotes that all {key,value} pairs following it
      belong in the Desktop Entry group.  There may be other groups present
      in the file (see MIME types discussion below), 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 proceeding this group in the
      desktop entry file but possibly one or more comments (see
      below).
    </para>
    <para>
      Group headers may not contain the characters '[' and ']' as
      those delimit the header.
    </para>
    <para>
      Lines beginning with a "#" are considered comments and will be
      ignored, however they should be preserved across reads / writes of the
      desktop entry 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>
    <para>
      Entries in the file are {key,value} pairs in the format:
    </para>
    <programlisting>
Name=Value</programlisting>
    <para>
      Space before and after the equals sign should be ignored; the "="
      sign is the actual delimiter.
    </para>
    <para>
      The escape sequences \s, \n, \t, \r, and \\ are supported,
      meaning ASCII space, newline, tab, carriage return, and
      backslash, respectively.
    </para>
  </sect1>
  <sect1 id="value-types">
    <title>Possible value types</title>
    <para>
      The value types recognized are string, localestring, regular expression,
      boolean (encoded as the string true/false), and numeric.
    </para>
    <para>
      The difference between string and localestring is that the value for
      a string key must contain only UTF-8 characters and while the value
      of a localestring key may contain localized encodings. (See
      section 5.)
    </para>
    <para>
      Some keys can have multiple values; these should be separated by a
      semicolon.  Those keys which have several values should have a
      semicolon as the trailing character. For lists of strings, 
      semicolons are simply not allowed in the strings, there is no 
      escape mechanism.
    </para>
  </sect1>
  <sect1 id="recognized-keys">
    <title>Recognized desktop entry keys</title>
    <para>
      Keys 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 lang[_COUNTRY][.ENCODING],
      where either _COUNTRY or .ENCODING 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 LC_MESSAGES
      category against the <replaceable>locale</replaceable> postfixes of all occurrences of the key,
      with the .ENCODING part stripped. (The .ENCODING is used when the
      Encoding key for the desktop entry file is Legacy-Mixed, see
      <xref linkend="legacy-mixed"/>.)
    </para>
    <para>
      The matching is done as follows: if the current value of
      LC_MESSAGES is
      <replaceable>lang</replaceable>_<replaceable>country</replaceable>.<replaceable>encoding</replaceable>@<replaceable>modifier</replaceable>,
      then, if a key for
      <replaceable>lang</replaceable>_<replaceable>country</replaceable>
      is present, it will be used. Otherwise, if a key for
      <replaceable>lang</replaceable> is present, it will be used. If
      both of these are missing, the required key without a locale
      specified is used.  The encoding and modifier from the
      LC_MESSAGES value are ignored.
    </para>
    <para>
      For example, if the current value of the LC_MESSAGES category
      is de_DE, and the desktop file includes:
    </para>
    <programlisting>
 Name=Foo
 Name[de]=Foo auf Deutsch</programlisting>
    <para>
      Then the value used for the name key will be 'Foo auf Deutsch'. However,
      if a value is specified for Name[de_DE], then that will be used
      instead.
    </para>
    <para>
      Case is significant.  The keys "Name" and "NAME" are not equivalent.
      The same holds for group names.  Key values are case sensitive as
      well.
    </para>
    <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.  Additionally, keys either MUST or MAY be
      supported by a particular implementation.
    </para>
    <para>
      Some keys only make sense in the context when another particular key
      is also present.
    </para>
    <para>
      Some example keys: Name[C], Comment[it].
    </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>MUST?</entry>
	  </row>
	</thead>
	<tbody>
	  <row>
	    <entry>Encoding</entry>
	    <entry>
	      encoding of the desktop entry  file
	    </entry>
	    <entry>string</entry>
	    <entry>YES</entry>
	    <entry>YES</entry>
	  </row>
	  <row>
	    <entry>Version</entry>
	    <entry>
	      version of Desktop Entry Specification
	    </entry>
	    <entry>numeric (4)</entry>
	    <entry>NO</entry>
	    <entry>YES</entry>
	  </row>
	  <row>
	    <entry>Name</entry>
	    <entry>
              specific name of the application, for example "Mozilla"
	    </entry>
	    <entry>localestring</entry>
	    <entry>YES</entry>
	    <entry>YES</entry>
	  </row>
	  <row>
	    <entry>GenericName</entry>
	    <entry>
              generic name of the application, for example "Web Browser"
	    </entry>
	    <entry>localestring</entry>
	    <entry>YES</entry>
	    <entry>YES</entry>
	  </row>
	  <row>
	    <entry>Type</entry>
	    <entry>
              the type of desktop entry
	    </entry>
	    <entry>string (1)</entry>
	    <entry>YES</entry>
	    <entry>YES</entry>
	  </row>
	  <row>
	    <entry>FilePattern</entry>
	    <entry>
              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.
	    </entry>
	    <entry>regexp(s)</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>TryExec</entry>
	    <entry>
              filename 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>NO</entry>
	  </row>
	  <row>
	    <entry>NoDisplay</entry>
	    <entry>
              whether not to display in menus, etc.
	    </entry>
	    <entry>boolean</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>Comment</entry>
	    <entry>
              tooltip for the entry, for example "View sites on the
              Internet"; should not be redundant with Name or 
              GenericName.
	    </entry>
	    <entry>localestring</entry>
	    <entry>NO</entry>
	    <entry>YES</entry>
	  </row>
	  <row>
	    <entry>Exec</entry>
	    <entry>
              program to execute, possibly with arguments
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>YES</entry>
	  </row>
	  <row>
	    <entry>Actions</entry>
	    <entry>
              additional actions possible, see MIME type discussion
	      in <xref linkend="mime-types"/>
	    </entry>
	    <entry>string(s)</entry>
	    <entry>NO</entry>
	    <entry>YES</entry>
	  </row>
	  <row>
	    <entry>Icon</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, an
              implementation-dependent search algorithm will be used
              to locate the icon. Icons may be localized with the
              Icon[xx]= syntax, but filenames should be in UTF-8, not
              locale encoding.
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>YES</entry>
	  </row>
	  <row>
	    <entry>MiniIcon</entry>
	    <entry>
              small icon for menus, etc (deprecated).
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>Hidden</entry>
	    <entry>
              if true, pretend this entry doesn't exist.
	    </entry>
	    <entry>boolean</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>Path</entry>
	    <entry>
              if entry is type Application, the working directory to run the program in.
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>YES</entry>
	  </row>
	  <row>
	    <entry>Terminal</entry>
	    <entry>
              whether the program runs in a terminal window
	    </entry>
	    <entry>boolean (2)</entry>
	    <entry>NO</entry>
	    <entry>YES</entry>
	  </row>
	  <row>
	    <entry>TerminalOptions</entry>
	    <entry>
              if the program runs in a terminal, any options that
              should be passed to the terminal emulator before
              actually executing the program. This field is 
              deprecated because it's dependent on which emulator
              is used.
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>SwallowTitle</entry>
	    <entry>
              if entry is swallowed onto the panel, this should be the title of window
	    </entry>
	    <entry>localestring</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>SwallowExec</entry>
	    <entry>
              program to exec if swallowed app is clicked
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>MimeType</entry>
	    <entry>
              the MIME type(s) supported by this entry
	    </entry>
	    <entry>regexp(s)</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>Patterns</entry>
	    <entry>
              if entry is type MimeType, various file name extensions
              associated with the MIME type.
	    </entry>
	    <entry>regexp(s)</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>DefaultApp</entry>
	    <entry>
              if entry is type MimeType, the default application associated with this mime type
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>Dev</entry>
	    <entry>
              if FSDevice type of entry, the device to mount
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>FSType</entry>
	    <entry>
              The type of filesystem to try to mount
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>MountPoint</entry>
	    <entry>
              if FSDevice type of entry, the mount point of the device in question
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>ReadOnly</entry>
	    <entry>
              if FSDevice type of entry, specifies whether or not the device is read-only
	    </entry>
	    <entry>boolean (2)</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>UnmountIcon</entry>
	    <entry>
              icon to display when device is not mounted Mounted devices display icon from Icon key
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>SortOrder</entry>
	    <entry>
              if entry of type Directory, this may specify the order in which to display files
	    </entry>
	    <entry>strings (3)</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>URL</entry>
	    <entry>
              if entry is Link type, the URL to access
	    </entry>
	    <entry>string    </entry>
	    <entry>NO</entry>
	    <entry>YES</entry>
	  </row>
	  <row>
	    <entry>BinaryPattern</entry>
	    <entry>
              Deprecated.
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>DocPath</entry>
	    <entry>
              Deprecated.
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>Extensions</entry>
	    <entry>
              Deprecated.
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>InitialPreference</entry>
	    <entry>
              Deprecated.
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>Keywords</entry>
	    <entry>
              Deprecated.
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>MapNotify</entry>
	    <entry>
              Deprecated.
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>Protocols</entry>
	    <entry>
              Deprecated.
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	  <row>
	    <entry>ServiceTypes</entry>
	    <entry>
              Deprecated.
	    </entry>
	    <entry>string</entry>
	    <entry>NO</entry>
	    <entry>NO</entry>
	  </row>
	</tbody>
      </tgroup>
    </table>
    <para>
      Notes:
    </para>
    <orderedlist>
      <listitem>
	<para>
	  possible values are Application, Link, FSDevice, MimeType, Directory,
	  Service, ServiceType
	</para>
      </listitem>
      <listitem>
	<para>
	  historically these have been represented by the numeric entries 0
	  or 1.  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 0 and 1 as false
	  and true, respectively.
	</para>
      </listitem>
      <listitem>
	<para>
	  historically this has been a comma separated list.  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>
      <listitem>
	<para>
	  while the version field is not required to be present, it should
	  be in all newer implementations of the Desktop Entry specification.
	  If the version number is not present, a "pre-standard" desktop entry
	  file is to be assumed.
	</para>
      </listitem>
    </orderedlist>
  </sect1>
  <sect1 id="character-encoding">
    <title>Character set encoding of the file</title>
    <para>
      Desktop entry files are encoded as lines of 8-bit characters separated
      by LF characters.
    </para>
    <para>
      Except for comments and values of type localestring, only ASCII 
      characters are permitted in the file:
    </para>
    <itemizedlist>
      <listitem>
	<para>
	  Key names must contain only the characters 'A-Za-z0-9-'
	</para>
      </listitem>
      <listitem>
	<para>
	  Group names may contain all ASCII characters except for control 
	  characters and '[' and ']'.
	</para>
      </listitem>
      <listitem>
	<para>
	  Values of type string may contain all ASCII characters except
	  for control characters.
	</para>
      </listitem>
      <listitem>
	<para>
	  Values of type boolean must either be the string 'true' or
	  'false'
	</para>
      </listitem>
      <listitem>
	<para>
	  Numeric values must be a valid floating point number as recognized
	  by the %f specifier for scanf.
	</para>
      </listitem>
    </itemizedlist>
    <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>
    <para>
      The encoding for values of type localestring is determined by the
      Encoding field of the desktop entry. This field should always
      be present. (However, many legacy files may not include it.)
    </para>
    <para>
      Only two values for Encoding are currently defined: 'UTF-8', and 
      'Legacy-Mixed', and desktop files must not use any other value.
      Implementations must support the UTF-8 encoding, and may choose
      to support Legacy-Mixed in addition. For this reason, authors
      of desktop files are encouraged to use the value 'UTF-8'.
    </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 Encoding line, 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 filesystem
	</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 Encoding key in the same way as a file with an
      unsupported Encoding Key.
    </para>
  </sect1>
  <sect1 id="exec-variables">
    <title>List of valid Exec parameter variables</title>
    <para>
      Each "Exec" field may take a number of arguments which will be
      expanded by the file manager or program launcher and passed to the
      program if necessary.
    </para>
    <para>
      Literal % characters must be escaped as %%, and adding new
      format characters is not allowed. It's a fatal error to have an
      Exec field with a format character not given in the spec.
      Again for emphasis: <emphasis>nonstandard extensions are 
      not allowed here - you must add an X-Foo-Exec field if you have
      nonstandard Exec lines</emphasis>.
    </para>
    <para>
    Recognized fields are as follows:
    </para>
    <informaltable>
      <tgroup cols="2">
	<tbody>
	  <row>
	    <entry>%f</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. HTTP or FTP locations), the files will be copied to the local
	      file system and %f will be expanded to point at the temporary
	      file. Used for programs that do not understand URL syntax.
	    </entry>
	  </row>
	  <row>
	    <entry>%F</entry>
	    <entry>
	      a list of files. Use for apps that can open several local
	      files at once.
	    </entry>
	  </row>
	  <row>
	    <entry>%u</entry>
	    <entry>
	      a single URL.
	    </entry>
	  </row>
	  <row>
	    <entry>%U</entry>
	    <entry>
	      a list of URLs.
	    </entry>
	  </row>
	  <row>
	    <entry>%d</entry>
	    <entry>
              directory containing the file that would be passed in a %f field
	    </entry>
	  </row>
	  <row>
	    <entry>%D</entry>
	    <entry>
              list of directories containing the files that would be
              passed in to a %F field
	    </entry>
	  </row>
	  <row>
	    <entry>%n</entry>
	    <entry>
	      a single filename (without path)
	    </entry>
	  </row>
	  <row>
	    <entry>%N</entry>
	    <entry>
	      a list of filenames (without path)
	    </entry>
	  </row>
	  <row>
	    <entry>%i</entry>
	    <entry>
	      the icon associated with the desktop entry
	    </entry>
	  </row>
	  <row>
	    <entry>%m</entry>
	    <entry>
	      the mini-icon associated with the desktop entry
	    </entry>
	  </row>
	  <row>
	    <entry>%c</entry>
	    <entry>
	      the comment associated with the desktop entry
	    </entry>
	  </row>
	  <row>
	    <entry>%k</entry>
	    <entry>
	      the name of the desktop file
	    </entry>
	  </row>
	  <row>
	    <entry>%v</entry>
	    <entry>
	      the name of the Device entry in the desktop file
	    </entry>
	  </row>
	</tbody>
      </tgroup>
    </informaltable>
  </sect1>
  <sect1 id="mime-types">
    <title>Detailed discussion of supporting MIME types</title>
    <para>
      It is in every desktop's best interest to have thorough support for
      mime types.  The old /etc/mailcap and /etc/mime.types files are rather
      limited in scope and frankly, are outdated.  Various desktop systems
      have come up with different ways of extending this original system,
      but none are compatible with each other.  The Desktop Entry Standard
      hopes to be able to provide the beginnings of a solution to this
      problem.
    </para>
    <para>
      At a very basic level, the "Exec" key provides the default action to
      take when the program described by a desktop entry is used to open a
      document or data file.  Usually this consists of some action along the
      lines of "kedit %f" or "ee %f".  This is a good
      start, but it isn't as flexible as it can be.
    </para>
    <para>
      Let us first establish that a program which supports a MIME type or
      multiple mime types may be able to support multiple actions on those
      MIME types as well.  The desktop entry may want to define additional
      actions in addition to the default.  The toplevel "Exec" key describes
      the default action; Let us define this action to also be known as the
      "Open" action.  Additional actions which might be possible include
      View, Edit, Play, etc.  A further revision of this document will
      probably specify several "standard" actions in addition to the default
      "Open" action, but in all cases, the number of actions is
      arbitrary.
    </para>
    <para>
      Let us use a sound player as a simple example.  Call it sp.  The
      default Exec (Open) action for this program would likely look
      something like:
    </para>
    <programlisting>
Exec=sp %u</programlisting>
    <para>
      However, imagine the sound player also supports editing of sound files
      in a graphical manner.  We might wish to define an additional action
      which could accomodate this.  Adding the action would be performed
      like this:
    </para>
    <programlisting>
Actions=Edit;

[Desktop Action Edit]
Exec=sp -edit %u</programlisting>
    <para>
      As you can see, defining the action "edit" will enable an additional
      group of the name [Desktop Action <replaceable>actionname</replaceable>] to be read.  This
      group can contain an additional Exec line, as well as possibly other
      information like a new Name, Comment, Icon, and Path.  Thus
      right-clicking on a .wav file will show both the default "Open" action
      and this "Edit" action to both be displayed as choices in the
      context-menu.  A left click (double or single, whichever the file
      manager implements) would cause the default action to take place.
      These are implementation-specific details which are up to the
      implementer, and are not enforced by this standard.
    </para>
    <para>
      If no DefaultApp is specified for a particular MIME type, any one of
      the programs registered which claim to be able to handle the MIME type
      may become the default handler.  This behaviour is undefined and
      implementation-specific. KDE doesn't use a DefaultApp anymore, but assigns
      a Preference number to each program, so that the highest number is the
      one chosen for handling the MIME type.
    </para>
  </sect1>
  <sect1 id="extending">
    <title>Extending the format</title>
    <para>
      If the standard is to be amended with a new {key,value} 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 "X-PRODUCT",
      i.e. "X-NewDesktop-Foo", 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. [X-PRODUCT GROUPNAME] 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
Actions=Edit;Inverse
Icon=fooview.png
MimeType=image/x-foo
X-KDE-Library=libfooview
X-KDE-FactoryName=fooviewfactory
X-KDE-ServiceType=FooService

[Desktop Action Inverse]
Exec=fooview --inverse %f
Name=Foo Viewer (inverse image)

[Desktop Action Edit]
Exec=fooview --edit %f
Name=Foo Viewer (edit image)
Icon=fooview-edit.png</programlisting>
  </appendix>
  <appendix id="legacy-mixed">
    <title>The Legacy-Mixed encoding</title>
    <para>
      The Legacy-Mixed 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 localestring key
      is determined by the locale tag for that key, if any. For keys
      without a locale tag, the value must contain only ASCII 
      characters.
    </para>
    <para>
      If the locale tag includes an .ENCODING part, then that determines
      the encoding for the line. Otherwise, the encoding is determined
      by the language, or language-country pair from the locale tag, according
      to the following table. (A language-country locale tag matches a
      language by itself in the table if the language-country pair isn't
      explicitely in the 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 wa no pt sv</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>ga cy</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
	    iconv 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
      ENCODING part of the locale tag.
    </para>
    <para>
      Matching the ENCODING 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, "Big5" is frequently
      found instead of "BIG5" and "georgianacademy" instead of
      GEORGIAN-ACADEMY. Desktop files creators should, however, use
      the name as it appears in the "Encoding" column above.
    </para>
  </appendix>
</article>