path: root/menu/menu-spec.xml

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<article id="index">
  <articleinfo>
    <title>Desktop Menu Specification</title>
    <releaseinfo>Version 0.9</releaseinfo>
    <date>8 December 2004</date>
    <authorgroup>
      <author>
	<firstname>Waldo</firstname>
	<surname>Bastian</surname>
	<affiliation>
	  <address>
	    <email>bastian@kde.org</email>
	  </address>
	</affiliation>
      </author>
      <author>
	<firstname>Francois</firstname>
	<surname>Gouget</surname>
	<affiliation>
	  <address>
	    <email>fgouget@codeweavers.com</email>
	  </address>
	</affiliation>
      </author>
      <author>
	<firstname>Alex</firstname>
	<surname>Graveley</surname>
	<affiliation>
	  <address>
	    <email>alex@ximian.com</email>
	  </address>
	</affiliation>
      </author>
      <author>
	<firstname>George</firstname>
	<surname>Lebl</surname>
	<affiliation>
	  <address>
	    <email>jirka@5z.com</email>
	  </address>
	</affiliation>
      </author>
      <author>
	<firstname>Havoc</firstname>
	<surname>Pennington</surname>
	<affiliation>
	  <address>
	    <email>hp@pobox.com</email>
	  </address>
	</affiliation>
      </author>
      <author>
	<firstname>Heinrich</firstname>
	<surname>Wendel</surname>
	<affiliation>
	  <address>
	    <email>h_wendel@cojobo.net</email>
	  </address>
	</affiliation>
      </author>
    </authorgroup>
  </articleinfo>

  <sect1 id="introduction">
    <title>Introduction</title>
    <para>
      This DRAFT document defines how to construct a user-visible hierarchy of
      applications, typically displayed as a menu. It allows third-party
      software to add menu items that work for all desktops, and allows system
      administrators to edit menus in a way that affects all desktops.
    </para>
    <para>
      The basic scheme is very simple. Information about each application (menu
      item) is stored in a desktop entry (see <ulink
        url="http://www.freedesktop.org/standards/desktop-entry-spec">Desktop
      Entry Standard</ulink>).  Then an XML configuration file defines the
      hierarchical arrangement (layout) of menu items, and which menu items are
      actually displayed.
    </para>
    <para>
      Things are complicated somewhat by the need to support legacy desktop
      entry hierarchies, and the need to allow third parties to extend the menu
      layout. Both of these issues are addressed by the idea of
      <firstterm>merging</firstterm> two menu layouts.
    </para>
    <para>
      In addition to a strict definition of the contents of each menu this 
      specification also foresees in a number of layout / presentation hints.
      This part of the specification is optional, implementations may chose to
      ignore these hints.
    </para>
  </sect1>
  <sect1 id="paths">
    <title>File locations</title>
    <para>
      Files involved in this specification are located according to the "desktop
      base directory specification" which can be found on <ulink
      url="http://www.freedesktop.org/standards/">www.freedesktop.org</ulink>.
    </para>
    <para>
      Here are the files defined by this specification:
      <variablelist>
        <varlistentry>
          <term><varname>$XDG_CONFIG_DIRS</varname>/menus/applications.menu</term>
          <listitem>
            <para>
              This file contains the XML definition of the main application menu 
              layout. The first file found in the search path should be used;
              other files are ignored.  This implies that if the user has 
              their own applications.menu, it replaces the system wide one. 
              (Though the user's menu may explicitly merge the system wide one.)
            </para>
            <para>
              Other menu files may exist, but are not specified in this
              document.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>$XDG_CONFIG_DIRS</varname>/menus/<replaceable>menu-file-basename</replaceable>-merged/</term>
          <listitem>
            <para>
              The default merge directories included in the
              &lt;DefaultMergeDirs&gt; element.  By convention, third parties
              may add new &lt;Menu&gt; files in this
              location. <replaceable>menu-file-basename</replaceable> means the
              "applications" from "applications.menu" for example. So the merge
              directory would be "applications-merged".
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>$XDG_DATA_DIRS</varname>/applications/</term>
          <listitem>
            <para>
              This directory contains a .desktop file for each possible menu
              item. Each directory in the <varname>$XDG_DATA_DIRS</varname>
              search path should be used (i.e. desktop entries are collected
              from all of them, not just the first one that exists). When two
              desktop entries have the same name, the one appearing earlier in
              the path is used.
            </para>
            <para>
              The &lt;DefaultAppDirs&gt; element in a menu file indicates that
              this default list of desktop entry locations should be scanned at
              that point. If a menu file does not contain
              &lt;DefaultAppDirs&gt;, then these locations are not scanned.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>$XDG_DATA_DIRS</varname>/desktop-directories/</term>
          <listitem>
            <para>
              This directory contains directory entries which may be associated 
              with folders in the menu layout. Each directory 
              in the search path should be used. Only files ending in 
              .directory are used; other files are ignored.
            </para>
            <para>
              The &lt;DefaultDirectoryDirs&gt; element in a menu file indicates that
              this default list of directory entry locations should be scanned at
              that point. If a menu file does not contain
              &lt;DefaultDirectoryDirs&gt;, then these locations are not scanned.
            </para>
          </listitem>
        </varlistentry>
      </variablelist>
    </para>
  </sect1>
  <sect1 id="desktop-entry-extensions">
    <title>Extensions to the desktop entry format</title>
    <para>
      This specification adds three new fields to <ulink
url="http://www.freedesktop.org/standards/desktop-entry-spec">desktop
entries</ulink>: <varname>Categories</varname>,
      <varname>OnlyShowIn</varname> and <varname>NotShowIn</varname>.
    </para>
    <para>
      The <varname>Categories</varname> field is a list of strings used to
      classify menu items. For example, applications in the
      <literal>AudioVideo</literal> category might end up in the "Sound &amp;
	  Video" submenu. <xref linkend="category-registry"/> enumerates the 
      standard categories. Categories not in this document must be prefixed
      by the string "X-" indicating that they are extensions. Categories 
      are case-sensitive.
    </para>
    <para>
      Desktop entries should list all categories that clearly apply. They should
      not list categories that only vaguely or possibly apply, because the user
      will end up seeing the same desktop entry in a half-dozen places. But
      it's typical that several categories will apply to a given desktop entry.
    </para>
    <para>
      The <varname>OnlyShowIn</varname> field is a list of strings identifying
      the environments that should display a given menu item.  If an
      <varname>OnlyShowIn</varname> field is present, a given environment should
      only display the menu item if the string identifying that environment is
      present.  The strings are case-sensitive. <xref
	  linkend="onlyshowin-registry"/> enumerates the strings to use for
      some common environments.
    </para>
    <para>
      The <varname>NotShowIn</varname> field is a list of strings identifying
      the environments that should not display a given menu item.  If an
      <varname>NotShowIn</varname> field is present, a given environment should
      only display the menu item if the string identifying that environment is
      not present.  The strings are case-sensitive. <xref
	  linkend="onlyshowin-registry"/> enumerates the strings to use for
      some common environments.
    </para>
    <sect2 id="desktop-entry-extensions-examples">
      <title>Examples of using <varname>Categories</varname> and <varname>OnlyShowIn</varname></title>
      <para>
        A desktop entry for a Qt-based image viewer might contain 
        this <varname>Categories</varname> line:
        <informalexample>
          <programlisting>
            Categories=Qt;Graphics;RasterGraphics;Viewer;
          </programlisting>
        </informalexample>
      </para>
      <para>
        A desktop entry for Octave, a command-line mathematics program (which
        would also have the field <literal>Terminal=true</literal>), might have:
        <informalexample>
          <programlisting>
            Categories=ConsoleOnly;Math;
          </programlisting>
        </informalexample>
      </para>
      <para>
        A desktop entry for a GNOME-specific calculator program
        that should only appear in GNOME might have:
        <informalexample>
          <programlisting>
            Categories=GNOME;Utility;
            OnlyShowIn=GNOME;
          </programlisting>
        </informalexample>
        Note that the <varname>OnlyShowIn</varname> field is a
        <emphasis>list</emphasis> and thus ends in a semicolon.
      </para>
    </sect2>
  </sect1>
  <sect1 id="menu-file-format">
    <title>Format of menu files</title>
    <para>
      Menu files must be well-formed XML files, conform to the menu file DTD,
      and end in the extension ".menu".  DTD conformance implies that
      implementation-specific extensions to the file format are not allowed;
      implementations are expected to stop processing if they encounter XML
      elements or attributes that are not specified in this document.
    </para>
    <sect2 id="menu-file-doctype">
      <title>Document Type Declaration</title>
      <para>
        Menu files for this version of the specification must use the following
        namespace, public and system identifiers:
        <variablelist>
          <varlistentry>
            <term>Namespace</term>
            <listitem>
              <para>
                <literal>http://www.freedesktop.org/standards/menu</literal>
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>Public Identifier for 0.8</term>
            <listitem>
              <para>
                <literal>PUBLIC "-//freedesktop//DTD Menu 0.8//EN"</literal>
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>System Identifier for 0.8</term>
            <listitem>
              <para>
                <literal>http://www.freedesktop.org/standards/menu-spec/menu-0.8.dtd</literal>
              </para>
            </listitem>
          </varlistentry>
        </variablelist>

        Here is a sample document type declaration:
        <informalexample>
          <programlisting>
            &lt;!DOCTYPE Menu PUBLIC "-//freedesktop//DTD Menu 0.8//EN"
            "http://www.freedesktop.org/standards/menu-spec/menu-0.8.dtd"&gt;
          </programlisting>
        </informalexample>
        
        All menu files MUST include the document type declaration, so that
        implementations can adapt to different versions of this specification
        (and so implementations can validate the menu file against 
        the DTD).
      </para>
    </sect2>
    <sect2 id="menu-file-elements">
      <title>Elements</title>
      <para>
        <variablelist>
          <varlistentry>
            <term>&lt;Menu&gt;</term>
            <listitem>
              <para>
                The root element is &lt;Menu&gt;.  Each &lt;Menu&gt; element may
                contain any number of nested &lt;Menu&gt; elements, indicating submenus.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;AppDir&gt;</term>
            <listitem>
              <para>
                This element may only appear below &lt;Menu&gt;. The
                content of this element is a directory name. Desktop entries
                in this directory are scanned and added to the pool of entries 
                which can be included in this &lt;Menu&gt; and its submenus.
                Only files ending in ".desktop" should be used, other files are
                ignored.
              </para>
              <para>
                Desktop entries in the pool of available entries are identified
                by their <firstterm>desktop-file id</firstterm> (see <xref
				linkend="term-desktop-file-id"/>). 
                The desktop-file id of a desktop entry is equal to its filename, 
                with any path components removed.
                So given a &lt;AppDir&gt;
                <filename>/foo/bar</filename> and desktop entry
                <filename>/foo/bar/Hello.desktop</filename> the desktop
                entry would get a desktop-file id of <filename>Hello.desktop</filename>
              </para>
              <para>
                If the directory contains sub-directories then these sub-directories
                should be (recursively) scanned as well. The name of the subdirectory 
                should be added as prefix to the desktop-file id together with a dash character ("-")
                So given a &lt;AppDir&gt;
                <filename>/foo/bar</filename> and desktop entry
                <filename>/foo/bar/booz/Hello.desktop</filename> the desktop
                entry would get a desktop-file id of <filename>booz-Hello.desktop</filename>
                A desktop entry <filename>/foo/bar/bo/oz/Hello.desktop</filename> would result
                in a desktop-file id of <filename>bo-oz-Hello.desktop</filename>
              </para>
              <para>
                &lt;AppDir&gt; elements appearing later in the menu file have
                priority in case of collisions between desktop-file ids.
              </para>
              <para>
                If the filename given as an &lt;AppDir&gt; is not an absolute
                path, it should be located relative to the location of the menu
                file being parsed. 
              </para>
              <para>
                Duplicate &lt;AppDir&gt; elements (that specify the same
                directory) should be ignored, but the <emphasis>last</emphasis>
                duplicate in the file should be used when establishing the order
                in which to scan the directories. This is important when merging
				(see <xref linkend="merge-algorithm"/>). The order of
                &lt;AppDir&gt; elements with respect to &lt;Include&gt; and
                &lt;Exclude&gt; elements is not relevant, also to facilitate
                merging.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;DefaultAppDirs&gt;</term>
            <listitem>
              <para>
                This element may only appear below &lt;Menu&gt;. The element has
                no content. The element should be treated as if it were a list
                of &lt;AppDir&gt; elements containing the default app dir
                locations
                (<replaceable>datadir</replaceable>/applications/ etc.). When expanding 
                &lt;DefaultAppDirs&gt; to a list of &lt;AppDir&gt;, the default
                locations that are earlier in the search path go later in the
                &lt;Menu&gt; so that they have priority.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;DirectoryDir&gt;</term>
            <listitem>
              <para>
                This element may only appear below &lt;Menu&gt;. The content of
                this element is a directory name. Each directory listed in a
                &lt;DirectoryDir&gt; element will be searched for directory 
                entries to be used when resolving the &lt;Directory&gt; element
                for this menu and its submenus.
                If the filename given as a &lt;DirectoryDir&gt; is not an absolute path, 
                    it should be located relative to the location 
                    of the menu file being parsed.
              </para>
              <para>
                  Directory entries in the pool of available entries are identified
                  by their <firstterm>relative path</firstterm> (see <xref
				  linkend="term-relative-path"/>).
              </para>
              <para>
                If two directory entries have duplicate relative paths, the one from 
                the last (furthest down) element in the menu file must be used.
                Only files ending in the extension ".directory" should be 
                loaded, other files should be ignored.
              </para>
              <para>
                Duplicate &lt;DirectoryDir&gt; elements (that specify the same
                directory) are handled as with duplicate &lt;AppDir&gt;
                elements (the last duplicate is used).
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;DefaultDirectoryDirs&gt;</term>
            <listitem>
              <para>
                This element may only appear below &lt;Menu&gt;. The element has
                no content. The element should be treated as if it were a list
                of &lt;DirectoryDir&gt; elements containing the default desktop dir
                locations
                (<replaceable>datadir</replaceable>/desktop-directories/ etc.). The default
                locations that are earlier in the search path go later in the
                &lt;Menu&gt; so that they have priority.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;Name&gt;</term>
            <listitem>
              <para>
                Each &lt;Menu&gt; element must have a single &lt;Name&gt;
                element. The content of the &lt;Name&gt; element is a name to
                be used when referring to the given menu. Each submenu of a
                given &lt;Menu&gt; must have a unique name. &lt;Menu&gt;
                elements can thus be referenced by a menu path, for example
                "Applications/Graphics." The &lt;Name&gt; field must not contain
                the slash character ("/"); implementations should discard 
				any name containing a slash. See also <xref linkend="term-menu-path"/>.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;Directory&gt;</term>
            <listitem>
              <para>
                Each &lt;Menu&gt; element has any number of &lt;Directory&gt;
                elements. The content of the &lt;Directory&gt; element 
                is the relative path of a directory entry containing meta information 
                about the &lt;Menu&gt;, such as its icon and localized name.
                If no &lt;Directory&gt; is specified for a &lt;Menu&gt;, 
                its &lt;Name&gt; field should be used as the user-visible
                name of the menu.
              </para>
              <para>
                Duplicate &lt;Directory&gt; elements are allowed in order 
                to simplify menu merging, and allow user menus to override 
                system menus. The last &lt;Directory&gt; element to appear 
                in the menu file "wins" and other elements are ignored, 
                unless the last element points to a nonexistent directory 
                entry, in which case the previous element should be tried instead, 
                and so on.
              </para>              
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;OnlyUnallocated&gt; and &lt;NotOnlyUnallocated&gt;</term>
            <listitem>
              <para>
                Each &lt;Menu&gt; may contain any number of
                &lt;OnlyUnallocated&gt; and &lt;NotOnlyUnallocated&gt;
                elements. Only the last such element to appear is relevant, as
                it determines whether the &lt;Menu&gt; can contain any desktop
                entries, or only those desktop entries that do not match other
                menus. If neither &lt;OnlyUnallocated&gt; nor
                &lt;NotOnlyUnallocated&gt; elements are present, the default 
                is &lt;NotOnlyUnallocated&gt;.
              </para>
              <para>
                To handle &lt;OnlyUnallocated&gt;, the menu file must be
                analyzed in two conceptual passes. The first pass processes
                &lt;Menu&gt; elements that can match any desktop entry. During
                this pass, each desktop entry is marked as allocated according
                to whether it was matched by an &lt;Include&gt; rule in some
                &lt;Menu&gt;. The second pass processes only &lt;Menu&gt;
                elements that are restricted to unallocated desktop entries.
                During the second pass, queries may only match desktop entries
                that were not marked as allocated during the first pass.
                See <xref linkend="query-algorithm"/>.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;Deleted&gt; and &lt;NotDeleted&gt;</term>
            <listitem>
              <para>
                Each &lt;Menu&gt; may contain any number of &lt;Deleted&gt; and
                &lt;NotDeleted&gt; elements. Only the last such element to
                appear is relevant, as it determines whether the &lt;Menu&gt;
                has been deleted. If neither &lt;Deleted&gt; nor
                &lt;NotDeleted&gt; elements are present, the default is
                &lt;NotDeleted&gt;. The purpose of this element is to support
                menu editing. If a menu contains a &lt;Deleted&gt; element 
                not followed by a &lt;NotDeleted&gt; element, that menu 
                should be ignored.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;Include&gt;</term>
            <listitem>
              <para>
                An &lt;Include&gt; element is a set of rules attempting to match
                some of the known desktop entries.  The &lt;Include&gt; element
                contains a list of any number of matching rules.  Matching rules
                are specified using the elements &lt;And&gt;, &lt;Or&gt;,
                &lt;Not&gt;, &lt;All&gt;, &lt;Filename&gt;, and
                &lt;Category&gt;. Each rule in a list of rules has a logical OR
                relationship, that is, desktop entries which match any rule
                are included in the menu.
              </para>
              <para>
                &lt;Include&gt; elements must appear immediately under
                &lt;Menu&gt; elements. The desktop entries they match are
                included in the menu. &lt;Include&gt; and &lt;Exclude&gt;
                elements for a given &lt;Menu&gt; are processed in order,
                with queries earlier in the file handled first. This has
				implications for merging, see <xref linkend="merge-algorithm"/>.
				See <xref linkend="query-algorithm"/> for full details on 
                    how to process &lt;Include&gt; and &lt;Exclude&gt; elements.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;Exclude&gt;</term>
            <listitem>
              <para>
                Any number of &lt;Exclude&gt; elements may appear below a
                &lt;Menu&gt; element. The content of an &lt;Exclude&gt; element
                is a list of matching rules, just as with an
                &lt;Include&gt;. However, the desktop entries matched are
                removed from the list of desktop entries included so far.  (Thus
                an &lt;Exclude&gt; element that appears before any
                &lt;Include&gt; elements will have no effect, for example, as no
                desktop entries have been included yet.)
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;Filename&gt;</term>
            <listitem>
              <para>
                The &lt;Filename&gt; element is the most basic matching rule.
                It matches a desktop entry if the desktop entry has the given
                desktop-file id. See <xref linkend="term-desktop-file-id"/>.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;Category&gt;</term>
            <listitem>
              <para>
                The &lt;Category&gt; element is another basic matching
                predicate. It matches a desktop entry if the desktop entry has
                the given category in its <varname>Categories</varname> field.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;All&gt;</term>
            <listitem>
              <para>
                The &lt;All&gt; element is a matching rule that matches 
                all desktop entries.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;And&gt;</term>
            <listitem>
              <para>
                The &lt;And&gt; element contains a list of matching rules. 
                If each of the matching rules inside the &lt;And&gt;
                element match a desktop entry, then the entire 
                &lt;And&gt; rule matches the desktop entry.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;Or&gt;</term>
            <listitem>
              <para>
                The &lt;Or&gt; element contains a list of matching rules. 
                If any of the matching rules inside the &lt;Or&gt;
                element match a desktop entry, then the entire 
                &lt;Or&gt; rule matches the desktop entry.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;Not&gt;</term>
            <listitem>
              <para>
                The &lt;Not&gt; element contains a list of matching rules.  If
                any of the matching rules inside the &lt;Not&gt; element matches
                a desktop entry, then the entire &lt;Not&gt; rule does
                <emphasis>not</emphasis> match the desktop entry. That is,
                matching rules below &lt;Not&gt; have a logical OR relationship.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;MergeFile&gt;</term>
            <listitem>
              <para>
                  Any number of &lt;MergeFile&gt; elements may be listed below a
                  &lt;Menu&gt; element, giving the name of another menu file to
				  be merged into this one. <xref linkend="merge-algorithm"/>
                  specifies how merging is done. The root &lt;Menu&gt; of the
                  merged file will be merged into the immediate parent of the
                  &lt;MergeFile&gt; element. The &lt;Name&gt; element of the
                  root &lt;Menu&gt; of the merged file are ignored. If the
                  filename given as a &lt;MergeFile&gt; is not an absolute path,
                  it should be located relative to the location of the menu file
                  being parsed.
              </para>
              <para>
                Duplicate &lt;MergeFile&gt; elements (that specify the same
                file) are handled as with duplicate &lt;AppDir&gt;
                elements (the last duplicate is used).
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;MergeDir&gt;</term>
            <listitem>
              <para>
                Any number of &lt;MergeDir&gt; elements may be listed below a
                &lt;Menu&gt; element. A &lt;MergeDir&gt; contains the name of a
                directory. Each file in the given directory which ends in the
                ".menu" extension should be merged in the same way that a
                &lt;MergeFile&gt; would be.  If the filename given as a
                &lt;MergeDir&gt; is not an absolute path, it should be located
                relative to the location of the menu file being parsed.
                The files inside the merged directory are not merged in any 
                specified order.
              </para>
              <para>
                Duplicate &lt;MergeDir&gt; elements (that specify the same
                directory) are handled as with duplicate &lt;AppDir&gt;
                elements (the last duplicate is used).
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;DefaultMergeDirs&gt;</term>
            <listitem>
              <para>
                This element may only appear below &lt;Menu&gt;. The element has
                no content. The element should be treated as if it were a list
                of &lt;MergeDir&gt; elements containing the default merge
                directory locations. When expanding &lt;DefaultMergeDirs&gt; to a
                list of &lt;MergeDir&gt;, the default locations that are earlier
                in the search path go later in the &lt;Menu&gt; so that they
                have priority.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;LegacyDir&gt;</term>
            <listitem>
              <para>
                This element may only appear below &lt;Menu&gt;. The text
                content of this element is a directory name.  Each directory
                listed in a &lt;LegacyDir&gt; element will be an old-style
                legacy hierarchy of desktop entries, see <xref
				linkend="legacy-hierarchies"/> for how to load such a
                hierarchy. Implementations must not load legacy hierarchies that
                are not explicitly specified in the menu file (because for
                example the menu file may not be the main menu).  If the
                filename given as a &lt;LegacyDir&gt; is not an absolute path,
                it should be located relative to the location of the menu file
                being parsed.
              </para>
              <para>
                Duplicate &lt;LegacyDir&gt; elements (that specify the same
                directory) are handled as with duplicate &lt;AppDir&gt;
                elements (the last duplicate is used).
              </para>
              <para>
                The &lt;LegacyDir&gt; element may have one attribute,
                <literal>prefix</literal>. Normally, given a &lt;LegacyDir&gt;
                <filename>/foo/bar</filename> and desktop entry
                <filename>/foo/bar/baz/Hello.desktop</filename> the desktop
                entry would get a desktop-file id of <filename>Hello.desktop</filename>.
                Given a prefix of <literal>boo-</literal>, it would instead be 
                assigned the desktop-file id <filename>boo-Hello.desktop</filename>. 
                The prefix should not contain path separator ('/') characters.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;KDELegacyDirs&gt;</term>
            <listitem>
              <para>
                This element may only appear below &lt;Menu&gt;. The element has
                no content. The element should be treated as if it were a list
                of &lt;LegacyDir&gt; elements containing the traditional desktop
                file locations supported by KDE with a hard coded prefix of "kde-". 
                When expanding &lt;KDELegacyDirs&gt; to a list of &lt;LegacyDir&gt;, the
                locations that are earlier in the search path go later in the
                &lt;Menu&gt; so that they have priority.
                The search path can be obtained by running <filename>kde-config --path apps</filename>
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;Move&gt;</term>
            <listitem>
              <para>
                This element may only appear below &lt;Menu&gt;.  The
                &lt;Move&gt; element contains pairs of &lt;Old&gt;/&lt;New&gt;
                elements indicating how to rename a descendant of the current
                &lt;Menu&gt;. If the destination path already exists, the moved
                menu is merged with the destination menu (see <xref
				linkend="merge-algorithm"/> for details).
              </para>
              <para>
                &lt;Move&gt; is used primarily to fix up legacy directories.
                For example, say you are merging a &lt;LegacyDir&gt; with folder
                names that don't match the current hierarchy; the legacy folder
                names can be moved to the new names, where they will be merged
                with the new folders.
              </para>
              <para>
                &lt;Move&gt; may or may not be useful for implementing menu 
				editing, see <xref linkend="menu-editing"/>.
              </para>
              <para>
                Duplicate &lt;Move&gt; elements are merged as specified in <xref
				linkend="merge-algorithm"/>.  Note that duplicates (two moves of
                the same path) can be detected easily because of the following
                rule: a move must reside at the lowest possible point.
              </para>
              <para>
                In other words, all moves have exactly one permissible location
                in the &lt;Menu&gt; hierarchy. Implementations can trivially
                detect violations of this rule: the &lt;Old&gt; and &lt;New&gt;
                paths may never share a common prefix. Moving "Foo/Bar" to
                "Foo/Baz" must be done with a &lt;Move&gt; element that's a
                child of the "Foo" &lt;Menu&gt;, i.e. by moving "Bar" to "Baz", not 
                by moving "Foo/Bar" to "Foo/Baz".
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;Old&gt;</term>
            <listitem>
              <para>
                This element may only appear below &lt;Move&gt;, and
                must be followed by a &lt;New&gt; element.  The content of both
                &lt;Old&gt; and &lt;New&gt; should be a menu path
                (slash-separated concatenation of &lt;Name&gt; fields, see 
				<xref linkend="term-menu-path"/>).
                Paths are interpreted relative to the menu containing 
                the &lt;Move&gt; element.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;New&gt;</term>
            <listitem>
              <para>
                This element may only appear below &lt;Move&gt;, and must
                be preceded by an &lt;Old&gt; element. The &lt;New&gt; element 
                specifies the new path for the preceding &lt;Old&gt; element.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;Layout&gt;</term>
            <listitem>
              <para>
                The &lt;Layout&gt; element is an optional part of this specification.
                Implementations that do not support the &lt;Layout&gt; element should
                preserve any &lt;Layout&gt; elements and their contents as far as
                possible.
                Each &lt;Menu&gt; may optionally contain a &lt;Layout&gt; element. 
                If multiple elements appear then only the last such element is relevant.
                The purpose of this element is to offer suggestions for the presentation
                of the menu. 
                If a menu does not contain a &lt;Layout&gt; element or if it contains
                an empty &lt;Layout&gt; element then the default layout should be used.
                The &lt;Layout&gt; element may contain &lt;Filename&gt;, &lt;Menuname&gt;,
                &lt;Separator&gt; and &lt;Merge&gt; elements. The &lt;Layout&gt; element
                defines a suggested layout for the menu starting from top to bottom.
                References to desktop entries that are not contained in this 
                menu as defined by the &lt;Include&gt; and &lt;Exclude&gt; elements should 
                be ignored. References to sub-menus that are not directly contained in this
                menu as defined by the &lt;Menu&gt; elements should be ignored.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;DefaultLayout [show_empty="false"] [inline="false"] [inline_limit="4"] [inline_header="true"] [inline_alias="false"]&gt;</term>
            <listitem>
              <para>
                The &lt;DefaultLayout&gt; element is an optional part of this specification.
                Implementations that do not support the &lt;DefaultLayout&gt; element should
                preserve any &lt;DefaultLayout&gt; elements and their contents as far as
                possible.
                Each &lt;Menu&gt; may optionally contain a &lt;DefaultLayout&gt; element
                which defines the default-layout for the current menu and all its sub-menus.
                If a menu has a &lt;DefaultLayout&gt; element then this will override
                any default-layout specified by a parent menu.
                The default-layout defines the suggested layout if a &lt;Menu&gt; element 
                does either not have &lt;Layout&gt; element or if it has an empty &lt;Layout&gt; element.
				For explanations of the various attributes see the &lt;Menuname&gt; element.
                If no default-layout has been specified then the layout as specified by the following
                elements should be assumed:
                &lt;DefaultLayout show_empty="false" inline="false" inline_limit="4" inline_header="true" inline_alias="false"&gt;&lt;Merge type="menus"/&gt;&lt;Merge type="files"/&gt;&lt;/DefaultLayout&gt;
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;Menuname [show_empty="..."] [inline="..."] [inline_limit="..."] [inline_header="..."] [inline_alias="..."]&gt;</term>
            <listitem>
              <para>
                This element may only appear as a child of a &lt;Layout&gt; or &lt;DefaultLayout&gt;
                menu. Its contents references an immediate sub-menu of the current menu as defined 
                with the &lt;Menu&gt; element, as such it should never contain a slash. 
                If no such sub-menu exists the element should be ignored.
				This element may have various attributes, the default values are taken from the DefaultLayout key.
                The show_empty attribute defines whether a menu that contains no desktop
                entries and no sub-menus should be shown at all. The show_empty attribute 
                can be "true" or "false".
                It may have an inline attribute that can be either "true" or "false".
                If the inline attribute is "true" the menu that is referenced may be copied into the 
                current menu at the current point instead of being inserted as sub-menu of the current menu.
                The optional inline_limit attribute defines the maximum number of entries that can be inlined.
                If the sub-menu has more entries than inline_limit, the sub-menu will not be inlined.
                If the inline_limit is 0 (zero) there is no limit.
                The optional inline_header attribute defines whether an inlined menu should be preceded with
                a header entry listing the caption of the sub-menu. 
                The inline_header attribute can be either "true" or "false".
                The optional inline_alias attribute defines whether a single inlined entry should adopt the
                caption of the inlined menu. In such case no additional header entry will be added regardless
                of the value of the inline_header attribute.
                The inline_alias attribute can be either "true" or "false".
                Example: if a menu has a sub-menu titled "WordProcessor" with a single entry "OpenOffice 4.2", 
                and both inline="true" and inline_alias="true" are specified then this would result in the 
                "OpenOffice 4.2" entry being inlined in the current menu but the "OpenOffice 4.2" caption 
                of the entry would be replaced with "WordProcessor".
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;Separator&gt;</term>
            <listitem>
              <para>
                This element may only appear as a child of a &lt;Layout&gt; or &lt;DefaultLayout&gt;
                menu. It indicates a suggestion to draw a visual separator at this point in the menu.
                &lt;Separator&gt; elements at the start of a menu, at the end of a menu or that directly
                follow other &lt;Separator&gt; elements may be ignored.
              </para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>&lt;Merge type="menus"|"files"|"all"/&gt;</term>
            <listitem>
              <para>
                This element may only appear as a child of a &lt;Layout&gt; or &lt;DefaultLayout&gt;
                menu. It indicates the point where desktop entries and sub-menus that are not explicitly 
                mentioned within the &lt;Layout&gt; or &lt;DefaultLayout&gt; element are to be inserted. 
                It has a type attribute that indicates which elements should be inserted: 
                type="menus" 
                means that all sub-menus that are not explicitly mentioned should be inserted in
                alphabetical order of their visual caption at this point. 
                type="files" 
                means that all desktop entries
                contained in this menu that are not explicitly mentioned should be inserted in
                alphabetical order of their visual caption at this point. 
                type="all" means that a mix of all sub-menus
                and all desktop entries that are not explicitly mentioned should be inserted in
                alphabetical order of their visual caption at this point.
                Each &lt;Layout&gt; or &lt;DefaultLayout&gt; element shall have exactly one &lt;Merge type="all"&gt;
                element or it shall have exactly one &lt;Merge type="files"&gt; and exactly one
                &lt;Merge type="menus"&gt; element. An exception is made for a completely empty &lt;Layout&gt; 
                element which may be used to indicate that the default-layout should be used instead.
              </para>
            </listitem>
          </varlistentry>
        </variablelist>
      </para>
    </sect2>
  </sect1>

  <sect1 id="merge-algorithm">
    <title>Merging</title>
    <para>
      Sometimes two menu layouts need to be merged. This is done when folding in
	  legacy menu hierarchies (see <xref linkend="legacy-hierarchies"/>) and also
      for files specified in &lt;MergeFile&gt; elements. A common case is that
      per-user menu files might merge the system menu file. Merging is also used
      to avoid cut-and-paste, for example to include a common submenu in
      multiple menu files.
    </para>
    <para>
      Merging involves a base &lt;Menu&gt; and a merged &lt;Menu&gt;. The base
      is the "target" menu and the merged &lt;Menu&gt; is being added to it. The
      result of the merge is termed the "combined menu."
    </para>
    <para>
      As a preparatory step, the goal is to resolve all files into 
      XML elements. To do so, traverse the entire menu tree. For each
      &lt;MergeFile&gt;, &lt;MergeDir&gt;, or &lt;LegacyDir&gt; element, replace
      the &lt;MergeFile&gt;, &lt;MergeDir&gt;, or &lt;LegacyDir&gt; element with
      the child elements of the root &lt;Menu&gt; of the file(s) being
      merged. As a special exception, remove the &lt;Name&gt; element from the
      root element of each file being merged. To generate a 
      &lt;Menu&gt; based on a &lt;LegacyDir&gt;, see 
	  <xref linkend="legacy-hierarchies"/>.
    </para>
    <para>
      Continue processing until no &lt;MergeFile&gt;, &lt;MergeDir&gt;, or
      &lt;LegacyDir&gt; elements remain, taking care to avoid infinite loops
      caused by files that reference one another.
    </para>
    <para>
      Once all files have been loaded into a single tree, scan the tree 
      recursively performing these steps to remove duplicates:
      <orderedlist>
        <listitem>
          <para>
            Consolidate child menus. Each group of child &lt;Menu&gt;s with the same
            name must be consolidated into a single child menu with that name.
            Concatenate the child elements of all menus with the same name, in
            the order that they appear, and insert those elements as the
            children of the <emphasis>last</emphasis> menu with that name.
            Delete all the newly empty &lt;Menu&gt; elements, keeping the 
            last one.
          </para>
        </listitem>
        <listitem>
          <para>
            Expand &lt;DefaultAppDirs&gt; and &lt;DefaultDirectoryDirs&gt; 
            elements to &lt;AppDir&gt; and &lt;DirectoryDir&gt; elements.
            Consolidate duplicate &lt;AppDir&gt;, &lt;DirectoryDir&gt;, 
            and &lt;Directory&gt; elements by keeping the last one.
            For &lt;Directory&gt; elements that refer to distinct directory 
            entries, all of them should be kept - if the last one points 
            to a nonexistent file, the one before that can be used instead, 
            and so forth.
          </para>
        </listitem>
        <listitem>
          <para>
            Resolve duplicate &lt;Move&gt; operations (with the same 
            origin path) by keeping the last one.
          </para>
        </listitem>
        <listitem>
          <para>
            Recurse into each child &lt;Menu&gt;, performing this list of 
            steps for each child in order.
          </para>
        </listitem>
      </orderedlist>
    </para>
    <para>
      After recursing once to remove duplicates, resolve &lt;Move&gt; elements
      for each menu starting with the top level and recursing into child menus.
      So the deepest menus have their &lt;Move&gt; operations performed last.
      Within each &lt;Menu&gt;, execute &lt;Move&gt; operations in the order
      that they appear. If the destination path does not exist, simply relocate
      the origin &lt;Menu&gt; element, and change its &lt;Name&gt; field to
      match the destination path.  If the origin path does not exist, do
      nothing.  If both paths exist, take the origin &lt;Menu&gt; element,
      delete its &lt;Name&gt; element, and prepend its remaining child elements
      to the destination &lt;Menu&gt; element.
    </para>
    <para>
      If any &lt;Move&gt; operations affect a menu, then re-run the 
      steps to resolve duplicates in case any duplicates have been 
      created.
    </para>
    <para>
      Finally, for each &lt;Menu&gt; containing a &lt;Deleted&gt; element which
      is not followed by a &lt;NotDeleted&gt; element, remove that menu and all
      its child menus.
    </para>

    <para>
      Merged menu elements are kept in order because &lt;Include&gt; and
      &lt;Exclude&gt; elements later in the file override &lt;Include&gt; and
      &lt;Exclude&gt; elements earlier in the file. This means that if the user's
      menu file merges the system menu file, the user can always override what
      the system menu specifies by placing elements after the &lt;MergeFile&gt;
      that incorporates the system file.
    </para>
    <para>
      To prevent that a desktop entry from one party inadvertently cancels out 
      the desktop entry from another party because both happen to get the same 
      desktop-file id it is recommended that providers of desktop-files ensure that
      all desktop-file ids start with a vendor prefix. A vendor prefix
      consists of [a-zA-Z] and is terminated with a dash ("-"). Open Source
      projects and commercial parties are encouraged  to use a word or phrase,
      preferably their name, as prefix for which they hold a trademark. Open Source
      applications can also ask to make use of the vendor prefix of another open
      source project (such as GNOME or KDE) they consider themselves affiliated
      with, at the discretion of these projects.
    </para>
    <para>
      For example, to ensure that GNOME applications start with a vendor prefix of "gnome-",
      it could either add "gnome-" to all the desktop files it installs in 
      <filename><replaceable>datadir</replaceable>/applications/</filename> or it could
      install desktop files in a <filename><replaceable>datadir</replaceable>/applications/gnome</filename>
      subdirectory. When including legacy menu hierarchies the <literal>prefix</literal> argument
      of the &lt;LegacyDir&gt; element can be used to specify a prefix.
    </para>
  </sect1>

  <sect1 id="query-algorithm">
    <title>Generating the menus</title>
    <para>
      After merging the menus, the result should be a single menu layout
      description.  For each &lt;Menu&gt;, we have a list of directories where
      desktop entries can be found, a list of directories where directory
      entries can be found, and a series of &lt;Include&gt; and &lt;Exclude&gt;
      directives.
    </para>
    <para>
      For each &lt;Menu&gt; element, build a pool of desktop entries by
      collecting entries found in each &lt;AppDir&gt; for the menu element.  If
      two entries have the same desktop-file id, the entry for the earlier (closer
      to the top of the file) &lt;AppDir&gt; must be discarded. Next, add to the
      pool the entries for any &lt;AppDir&gt;s specified by ancestor
      &lt;Menu&gt; elements. If a parent menu has a duplicate entry (same
      desktop-file id), the entry for the child menu has priority.
    </para>
    <para>
      Next, walk through all &lt;Include&gt; and &lt;Exclude&gt; statements.
      For each &lt;Include&gt;, match the rules against the pool of all desktop
      entries. For each desktop entry that matches one of the rules, 
      add it to the menu to be displayed and mark it as having been allocated.
      For each &lt;Exclude&gt;, match the rules against the currently-included
      desktop entries. For each desktop entry that matches, remove it again
      from the menu. Note that an entry that is included in a menu but excluded
      again by a later &lt;Exclude&gt; is still considered allocated (for the
      purposes of &lt;OnlyUnallocated&gt;) even though that entry no longer
      appears in the menu.
    </para>
    <para>
      Two passes are necessary, once for regular menus where any entry may
      be matched, and once for &lt;OnlyUnallocated&gt; menus where only entries
      which have not been marked as allocated may be matched.
    </para>
    <para>
      The result is a tree of desktop entries, of course.
    </para>
  </sect1>

  <sect1 id="legacy-hierarchies">
    <title>Legacy Menu Hierarchies</title>
    <para>
      Traditionally, menus were defined as a filesystem hierarchy, with each
      filesystem directory corresponding to a submenu.  Implementations of this
      specification must be able to load these old-style hierarchies
      as specified in this section.
    </para>
    <para>
      The general approach is: the legacy hierarchy is converted into a
      &lt;Menu&gt;, and then this menu layout is merged with the menu that
      specified &lt;LegacyDir&gt;.
    </para>
    <para>
      Desktop entries in the legacy hierarchy should be added to the pool of
      desktop entries as if the &lt;LegacyDir&gt; were an
      &lt;AppDir&gt;. Directory entries in the legacy hierarchy should be added
      to the pool of directory entries as if the &lt;LegacyDir&gt; were a
      &lt;DirectoryDir&gt;. This can be trivially implemented by adding
      appropriate &lt;AppDir&gt; and &lt;DirectoryDir&gt; statements to the root
      legacy &lt;Menu&gt;. There is one slight complexity, namely the 
      "prefix" attribute of &lt;LegacyDir&gt;.
    </para>
    <para>
      The menu layout corresponds conceptually to the following, though actually
      generating the XML is not necessary:
      <itemizedlist>
        <listitem>
          <para>
            For each directory in the legacy hierarchy, a 
            &lt;Menu&gt; is created with the same &lt;Name&gt; 
            as the directory on disk.
          </para>
        </listitem>
        <listitem>
          <para>
            This menu then contains an &lt;Include&gt; element that includes
            each desktop entry in the directory.  That is, it should have a 
            
            &lt;Filename&gt;<replaceable>Foo/Bar/foo.desktop</replaceable>&lt;/Filename&gt;
            for each desktop entry in the directory.
          </para>
          <para>
            As a special exception, if a desktop entry in a directory contains 
            a <varname>Categories</varname> field, that desktop entry should 
            <emphasis>not</emphasis> be included in the legacy menu.
            That is, no &lt;Include&gt; element should be generated for 
            the entry. This allows a desktop entry to be installed 
            in a legacy location but still work optimally with the
            menu system specified in this document.
          </para>
        </listitem>
        <listitem>
          <para>
            If the legacy directory contains a ".directory" file, then 
            a &lt;Directory&gt; element should be generated that points to said 
            ".directory" file. 
          </para>
        </listitem>
        <listitem>
          <para>
            Legacy desktop entries should not be assigned any
            <varname>Categories</varname> fields if they didn't have them
            already, except that all legacy entries should have the 
            "Legacy" category added to allow menu files to treat them 
            specially. (If the same directory is given as both 
            a &lt;LegacyDir&gt; and an &lt;AppDir&gt;, its desktop 
            entries should be labeled "Legacy" only if the &lt;LegacyDir&gt;
            appears later in the file than the &lt;AppDir&gt;.)
          </para>
        </listitem>
      </itemizedlist>
    </para>
    <para>
      For example, say we have the following legacy directory hierarchy:
      <informalexample>
        <programlisting>
          /usr/share/applnk
              /usr/share/applnk/.directory
              /usr/share/applnk/bar.desktop
              /usr/share/applnk/System
                  /usr/share/applnk/System/.directory
                  /usr/share/applnk/System/foo.desktop
        </programlisting>
      </informalexample>
      Conceptually that is converted to the following &lt;Menu&gt;:
      <informalexample>
        <programlisting>
          &lt;!DOCTYPE Menu PUBLIC "-//freedesktop//DTD Menu 0.8//EN"
          "http://www.freedesktop.org/standards/menu-spec/menu-0.8.dtd"&gt;

          &lt;Menu&gt;
            &lt;Name&gt;Applications&lt;/Name&gt;
            &lt;AppDir&gt;/usr/share/applnk&lt;/AppDir&gt;
            &lt;DirectoryDir&gt;/usr/share/applnk&lt;/DirectoryDir&gt;
            &lt;Directory&gt;.directory&lt;/Directory&gt;
            &lt;Include&gt;
              &lt;Filename&gt;bar.desktop&lt;/Filename&gt;
            &lt;/Include&gt;
            &lt;Menu&gt;
              &lt;Name&gt;System&lt;/Name&gt;
              &lt;AppDir&gt;/usr/share/applnk/System&lt;/AppDir&gt;
              &lt;DirectoryDir&gt;/usr/share/applnk/System&lt;/DirectoryDir&gt;
              &lt;Directory&gt;.directory&lt;/Directory&gt;
              &lt;Include&gt;
                &lt;Filename&gt;foo.desktop&lt;/Filename&gt;
              &lt;/Include&gt;
            &lt;/Menu&gt;
          &lt;/Menu&gt;
        </programlisting>
      </informalexample>
      This &lt;Menu&gt; is then merged as if it were in a file 
      and loaded with &lt;MergeFile&gt;.
    </para>
  </sect1>

  <sect1 id="example">
    <title>Example Menu File</title>
    <para>
      <informalexample>
        <programlisting>
          &lt;!DOCTYPE Menu PUBLIC "-//freedesktop//DTD Menu 0.8//EN"
          "http://www.freedesktop.org/standards/menu-spec/menu-0.8.dtd"&gt;

          &lt;Menu&gt;
            &lt;Name&gt;Applications&lt;/Name&gt;
            &lt;Directory&gt;Applications.directory&lt;/Directory&gt;
  
            &lt;-- Search the default locations --&gt;
            &lt;DefaultAppDirs/&gt;
            &lt;DefaultDirectoryDirs/&gt;
          
            &lt;-- Merge third-party submenus --&gt;
            &lt;MergeDir&gt;applications-merged&lt;/MergeDir&gt;

            &lt;-- Merge legacy hierarchy --&gt;
            &lt;LegacyDir&gt;/usr/share/applnk&lt;/LegacyDir&gt;

            &lt;-- Define default layout --&gt;
            &lt;DefaultLayout&gt;
              &lt;Merge type="menus"/&gt;
              &lt;Merge type="files"/&gt;
              &lt;Separator/&gt;
              &lt;Menuname&gt;More&lt;/Menuname&gt;
            &lt;/DefaultLayout&gt;

            &lt;-- some random moves, maybe to clean up legacy dirs, 
                   maybe from menu editing --&gt;
            &lt;Move&gt;
              &lt;Old&gt;Foo&lt;/Old&gt;
              &lt;New&gt;Bar&lt;/New&gt;
              &lt;Old&gt;Foo2&lt;/Old&gt;
              &lt;New&gt;Bar2&lt;/New&gt;
            &lt;/Move&gt;          

            &lt;-- A preferences submenu, kept in a separate file 
                   so it can also be used standalone --&gt;
            &lt;Menu&gt;
              &lt;Name&gt;Preferences&lt;/Name&gt;
              &lt;Directory&gt;Preferences.directory&lt;/Directory&gt;
              &lt;MergeFile&gt;preferences.menu&lt;/MergeFile&gt;
            &lt;/Menu&gt;

            &lt;-- An Office submenu, specified inline --&gt;
            &lt;Menu&gt;
              &lt;Name&gt;Office&lt;/Name&gt;
              &lt;Directory&gt;Office.directory&lt;/Directory&gt;
              &lt;Include&gt;
                &lt;Category&gt;Office&lt;/Category&gt;
              &lt;/Include&gt;
              &lt;Exclude&gt;
                &lt;Filename&gt;foo.desktop&lt;/Filename&gt;
              &lt;/Exclude&gt;
            &lt;/Menu&gt;
             
          &lt;/Menu&gt;
        </programlisting>
      </informalexample>
    </para>
  </sect1>

  <appendix id="category-registry">
    <title>Registered Categories</title>
    <para>
      Remember, these are case-sensitive. 
      When using a category described in the list below it is strongly 
      recommended to also include the category listed under Related 
      Categories. If a category has multiple related categories the most
      suitable related category should be included.
      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>Category</entry>
              <entry>Description</entry>
			  <entry>Related Categories</entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>Legacy</entry> 
              <entry>Keyword that must be added to menu
              entries merged from legacy locations. May not actually exist in a
              desktop entry (should be stripped out if found there). If the same
              directory is given as both a &lt;LegacyDir&gt; and an
              &lt;AppDir&gt;, its desktop entries should be labeled "Legacy"
              only if the &lt;LegacyDir&gt; appears later in the file than the
              &lt;AppDir&gt;</entry>

            </row><row>
              <entry>Core</entry>
              <entry>Important application, core to the desktop such as a file manager or a help browser</entry>
			  <entry></entry>

            </row><row>
              <entry>Development</entry>
              <entry>An application for development</entry>
			  <entry></entry>

            </row><row>
              <entry>Building</entry>
              <entry>A tool to build applications</entry>
			  <entry>Development</entry>

            </row><row>
              <entry>Debugger</entry>
              <entry>A tool to debug applications</entry>
			  <entry>Development</entry>

            </row><row>
              <entry>IDE</entry>
              <entry>IDE application</entry>
			  <entry>Development</entry>

            </row><row>
              <entry>GUIDesigner</entry>
              <entry>A GUI designer application</entry>
			  <entry>Development</entry>

            </row><row>
              <entry>Profiling</entry>
              <entry>A profiling tool</entry>
			  <entry>Development</entry>

            </row><row>
              <entry>RevisionControl</entry>
              <entry>Applications like cvs or subversion</entry>
			  <entry>Development</entry>

            </row><row>
              <entry>Translation</entry>
              <entry>A translation tool</entry>
			  <entry>Development</entry>

            </row><row>
              <entry>Office</entry>
              <entry>An office type application</entry>

            </row><row>
              <entry>Calendar</entry>
              <entry>Calendar application</entry>
			  <entry>Office</entry>

            </row><row>
              <entry>ContactManagement</entry>
              <entry>E.g. an address book</entry>
			  <entry>Office</entry>

            </row><row>
              <entry>Database</entry>
              <entry>Application to manage a database</entry>
			  <entry>Office or Development or AudioVideo</entry>

			</row><row>
              <entry>Dictionary</entry>
              <entry>A dictionary</entry>
			  <entry>Office</entry>

            </row><row>
              <entry>Chart</entry>
              <entry>Chart application</entry>
			  <entry>Office</entry>

            </row><row>
              <entry>Email</entry>
              <entry>Email application</entry>
			  <entry>Office;Network</entry>

            </row><row>
              <entry>Finance</entry>
              <entry>Application to manage your finance</entry>
			  <entry>Office</entry>

            </row><row>
              <entry>FlowChart</entry>
              <entry>A flowchart application</entry>
			  <entry>Office</entry>

            </row><row>
              <entry>PDA</entry>
              <entry>Tool to manage your PDA</entry>
			  <entry>Office</entry>

            </row><row>
              <entry>ProjectManagement</entry>
              <entry>Project management application</entry>
			  <entry>Office;Development</entry>

            </row><row>
              <entry>Presentation</entry>
              <entry>Presentation software</entry>
			  <entry>Office</entry>

            </row><row>
              <entry>Spreadsheet</entry>
              <entry>A spreadsheet</entry>
			  <entry>Office</entry>

            </row><row>
              <entry>WordProcessor</entry>
              <entry>A word processor</entry>
			  <entry>Office</entry>

            </row><row>
              <entry>Graphics</entry>
              <entry>Graphical application</entry>

            </row><row>
              <entry>2DGraphics</entry>
              <entry>2D based graphical application</entry>
			  <entry>Graphics</entry>

            </row><row>
              <entry>VectorGraphics</entry>
              <entry>Vector based graphical application</entry>
			  <entry>2DGraphics</entry>

            </row><row>
              <entry>RasterGraphics</entry>
              <entry>Raster based graphical application</entry>
			  <entry>2DGraphics</entry>

            </row><row>
              <entry>3DGraphics</entry>
              <entry>3D based graphical application</entry>
			  <entry>Graphics</entry>

            </row><row>
              <entry>Scanning</entry>
              <entry>Tool to scan a file/text</entry>
			  <entry>Graphics</entry>

            </row><row>
              <entry>OCR</entry>
              <entry>Optical character recognition application</entry>
			  <entry>Scanning</entry>

            </row><row>
              <entry>Photography</entry>
              <entry>Camera tools, etc.</entry>
			  <entry>Graphics or Office</entry>

            </row><row>
              <entry>Viewer</entry>
              <entry>Tool to view e.g. a graphic or pdf file</entry>
			  <entry>Graphics or Office</entry>

            </row><row>
              <entry>Settings</entry>
              <entry>Settings applications</entry>

            </row><row>
              <entry>DesktopSettings</entry>
              <entry>Configuration tool for the GUI</entry>
			  <entry>Settings</entry>

            </row><row>
              <entry>HardwareSettings</entry>
              <entry>A tool to manage hardware components, like sound cards, video cards or printers</entry>
			  <entry>Settings</entry>

            </row><row>
              <entry>PackageManager</entry>
              <entry>A package manager application</entry>
			  <entry>Settings</entry>

            </row><row>
              <entry>Network</entry>
              <entry>Network application such as a web browser</entry>
			  <entry>(Settings)</entry>

            </row><row>
              <entry>Dialup</entry>
              <entry>A dial-up program</entry>
			  <entry>Network</entry>

            </row><row>
              <entry>InstantMessaging</entry>
              <entry>An instant messaging client</entry>
			  <entry>Network</entry>

            </row><row>
              <entry>IRCClient</entry>
              <entry>An IRC client</entry>
			  <entry>Network</entry>

            </row><row>
              <entry>FileTransfer</entry>
              <entry>Tools like FTP or P2P programs</entry>
			  <entry>Network</entry>

            </row><row>
              <entry>HamRadio</entry>
              <entry>HAM radio software</entry>
			  <entry>Network or Audio</entry>

            </row><row>
              <entry>News</entry>
              <entry>A news reader or a news ticker</entry>

            </row><row>
              <entry>P2P</entry>
              <entry>A P2P program</entry>
			  <entry>Network</entry>

            </row><row>
              <entry>RemoteAccess</entry>
              <entry>A tool to remotely manage your PC</entry>
			  <entry>Network</entry>

            </row><row>
              <entry>Telephony</entry>
              <entry>Telephony via PC</entry>
			  <entry>Network</entry>

            </row><row>
              <entry>WebBrowser</entry>
              <entry>A web browser</entry>
			  <entry>Network</entry>

            </row><row>
              <entry>WebDevelopment</entry>
              <entry>A tool for web developers</entry>
			  <entry>Network or Development</entry>

            </row><row>
              <entry>AudioVideo</entry>
              <entry>A multimedia (audio/video) application</entry>

            </row><row>
              <entry>Audio</entry>
              <entry>An audio application</entry>
			  <entry>AudioVideo</entry>

            </row><row>
              <entry>Midi</entry>
              <entry>An app related to MIDI</entry>
			  <entry>Audio</entry>

            </row><row>
              <entry>Mixer</entry>
              <entry>Just a mixer</entry>
			  <entry>Audio</entry>

            </row><row>
              <entry>Sequencer</entry>
              <entry>A sequencer</entry>
			  <entry>Audio</entry>

            </row><row>
              <entry>Tuner</entry>
              <entry>A tuner</entry>
			  <entry>Audio</entry>

            </row><row>
              <entry>Video</entry>
              <entry>A video application</entry>
			  <entry>AudioVideo</entry>

            </row><row>
              <entry>TV</entry>
              <entry>A TV application</entry>
			  <entry>Video</entry>

            </row><row>
              <entry>AudioVideoEditing</entry>
              <entry>Application to edit audio/video files</entry>
			  <entry>Audio or Video or AudioVideo</entry>

            </row><row>
              <entry>Player</entry>
              <entry>Application to play audio/video files</entry>
			  <entry>Audio or Video or AudioVideo</entry>

            </row><row>
              <entry>Recorder</entry>
              <entry>Application to record audio/video files</entry>
			  <entry>Audio or Video or AudioVideo</entry>

            </row><row>
              <entry>DiscBurning</entry>
              <entry>Application to burn a disc</entry>
			  <entry>AudioVideo</entry>

            </row><row>
              <entry>Game</entry>
              <entry>A game</entry>

            </row><row>
              <entry>ActionGame</entry>
              <entry>An action game</entry>
			  <entry>Game</entry>

            </row><row>
              <entry>AdventureGame</entry>
              <entry>Adventure style game</entry>
			  <entry>Game</entry>

            </row><row>
              <entry>ArcadeGame</entry>
              <entry>Arcade style game</entry>
			  <entry>Game</entry>

            </row><row>
              <entry>BoardGame</entry>
              <entry>A board game</entry>
			  <entry>Game</entry>

            </row><row>
              <entry>BlocksGame</entry>
              <entry>Falling blocks game</entry>
			  <entry>Game</entry>

            </row><row>
              <entry>CardGame</entry>
              <entry>A card game</entry>
			  <entry>Game</entry>

            </row><row>
              <entry>KidsGame</entry>
              <entry>A game for kids</entry>
			  <entry>Game</entry>

            </row><row>
              <entry>LogicGame</entry>
              <entry>Logic games like puzzles, etc</entry>
			  <entry>Game</entry>

            </row><row>
              <entry>RolePlaying</entry>
              <entry>A role playing game</entry>
			  <entry>Game</entry>

            </row><row>
              <entry>Simulation</entry>
              <entry>A simulation game</entry>
			  <entry>Game</entry>

            </row><row>
              <entry>SportsGame</entry>
              <entry>A sports game</entry>
			  <entry>Game</entry>

            </row><row>
              <entry>StrategyGame</entry>
              <entry>A strategy game</entry>
			  <entry>Game</entry>

            </row><row>
              <entry>Education</entry>
              <entry>Educational software</entry>

            </row><row>
              <entry>Art</entry>
              <entry>Software to teach arts</entry>
			  <entry>Education</entry>

            </row><row>
              <entry>Construction</entry>
              <entry></entry>
			  <entry>Education</entry>

            </row><row>
              <entry>Music</entry>
              <entry>Musical software</entry>
			  <entry>AudioVideo;Education</entry>

            </row><row>
              <entry>Languages</entry>
              <entry>Software to learn foreign languages</entry>
			  <entry>Education</entry>

            </row><row>
              <entry>Science</entry>
              <entry>Scientific software</entry>
			  <entry>Education</entry>

            </row><row>
              <entry>Astronomy</entry>
              <entry>Astronomy software</entry>
			  <entry>Science</entry>

            </row><row>
              <entry>Biology</entry>
              <entry>Biology software</entry>
			  <entry>Science</entry>

            </row><row>
              <entry>Chemistry</entry>
              <entry>Chemistry software</entry>
			  <entry>Science</entry>

            </row><row>
              <entry>Geology</entry>
              <entry>Geology software</entry>
			  <entry>Science</entry>

            </row><row>
              <entry>Math</entry>
              <entry>Math software</entry>
			  <entry>Science</entry>

            </row><row>
              <entry>MedicalSoftware</entry>
              <entry>Medical software</entry>
			  <entry>Science</entry>

            </row><row>
              <entry>Physics</entry>
              <entry>Physics software</entry>
			  <entry>Science</entry>

            </row><row>
              <entry>Teaching</entry>
              <entry>An education program for teachers</entry>
			  <entry>Education</entry>

            </row><row>
              <entry>Amusement</entry>
              <entry>A simple amusement</entry>
			  <entry></entry>

            </row><row>
              <entry>Applet</entry>
              <entry>An applet that will run inside a panel or another such application, likely desktop specific</entry>
			  <entry></entry>

            </row><row>
              <entry>Archiving</entry>
              <entry>A tool to archive/backup data</entry>
			  <entry></entry>

            </row><row>
              <entry>Electronics</entry>
              <entry>Electronics software, e.g. a circuit designer</entry>
			  <entry></entry>

            </row><row>
              <entry>Emulator</entry>
              <entry>Emulator of another platform, such as a DOS emulator</entry>
			  <entry></entry>

            </row><row>
              <entry>Engineering</entry>
              <entry>Engineering software, e.g. CAD programs</entry>
			  <entry></entry>

            </row><row>
              <entry>FileManager</entry>
              <entry>A file manager</entry>
			  <entry></entry>

            </row><row>
              <entry>Shell</entry>
              <entry>A shell (an actual specific shell such as
              <filename>bash</filename> or <filename>tcsh</filename>, not a TerminalEmulator)</entry>

            </row><row>
              <entry>Screensaver</entry>
              <entry>A screen saver (launching this desktop entry should activate the screen saver)</entry>
			  <entry></entry>

            </row><row>
              <entry>TerminalEmulator</entry>
              <entry>A terminal emulator application</entry>
			  <entry></entry>

            </row><row>
              <entry>TrayIcon</entry>
              <entry>An application that is primarily an icon for the "system tray" or "notification area" (apps that open a normal window and just happen to have a tray icon as well should not list this category)</entry>
			  <entry></entry>

            </row><row>
              <entry>System</entry>
              <entry>System application, "System Tools" such as say a log viewer or network monitor</entry>
			  <entry>(Settings)</entry>

            </row><row>
              <entry>Filesystem</entry>
              <entry>A file system tool</entry>
			  <entry>System</entry>

            </row><row>
              <entry>Monitor</entry>
              <entry>Monitor application/applet that monitors some resource or activity</entry>
			  <entry>System</entry>

            </row><row>
              <entry>Security</entry>
              <entry>A security tool</entry>
			  <entry>Settings or System</entry>

            </row><row>
              <entry>Utility</entry>
              <entry>Small utility application, "Accessories"</entry>
			  <entry></entry>

            </row><row>
              <entry>Accessibility</entry>
              <entry>Accessibility</entry>
			  <entry>Settings or Utility</entry>

            </row><row>
              <entry>Calculator</entry>
              <entry>A calculator</entry>
			  <entry>Utility</entry>

            </row><row>
              <entry>Clock</entry>
              <entry>A clock application/applet</entry>
			  <entry>Utility</entry>

            </row><row>
              <entry>TextEditor</entry>
              <entry>A text editor</entry>
			  <entry>Utility</entry>

            </row><row>
              <entry>KDE</entry>
              <entry>Application based on KDE libraries</entry>
			  <entry>QT</entry>

            </row><row>
              <entry>GNOME</entry>
              <entry>Application based on GNOME libraries</entry>
			  <entry>GTK</entry>

            </row><row>
              <entry>GTK</entry>
              <entry>Application based on GTK+ libraries</entry>
			  <entry></entry>

            </row><row>
              <entry>Qt</entry>
              <entry>Application based on Qt libraries</entry>
			  <entry></entry>

            </row><row>
              <entry>Motif</entry>
              <entry>Application based on Motif libraries</entry>
			  <entry></entry>

            </row><row>
              <entry>Java</entry>
              <entry>Application based on Java GUI libraries, such as AWT or Swing</entry>
			  <entry></entry>

            </row><row>
              <entry>ConsoleOnly</entry>
              <entry>Application that only works inside a terminal (text-based or command line application)</entry>
			  <entry></entry>

            </row>
          </tbody>
        </tgroup>
      </informaltable>

    </para>
  </appendix>
  <appendix id="onlyshowin-registry">
    <title>Registered OnlyShowIn Environments</title>
    <para>
      Remember, these are case-sensitive. "KDE" not "kde" should be 
      used.
      <informaltable>
        <tgroup cols="2">
          <thead>
            <row>
              <entry>OnlyShowIn Value</entry>
              <entry>Environment</entry>
            </row>
          </thead>
          <tbody>
            <row>
              <entry>GNOME</entry><entry>GNOME Desktop</entry>
            </row><row>
              <entry>KDE</entry><entry>KDE Desktop</entry>
            </row><row>
              <entry>ROX</entry><entry>ROX Desktop</entry>
            </row><row>
              <entry>XFCE</entry><entry>XFCE Desktop</entry>
            </row><row>
              <entry>Old</entry><entry>Legacy menu systems</entry>
            </row>
          </tbody>
        </tgroup>
      </informaltable>
    </para>
  </appendix>
  <appendix id="third-party-howto">
    <title>How to add your application to the menus</title>
    <para>
      The short answer for third party applications is:
      <itemizedlist>
        <listitem>
          <para>
            Install desktop entries to
            <replaceable>datadir</replaceable>/applications/ for each menu
            item. Please namespace the filename, as in "vendor-foo.desktop", or
            use a subdirectory of
            <replaceable>datadir</replaceable>/applications/ so you have
            "vendor/foo.desktop." Please be sure all desktop entries are valid
            (see the <ulink
            url="http://www.freedesktop.org/software/desktop-file-utils/">
            desktop-file-utils</ulink> package for a validation utility).
          </para>
        </listitem>
        <listitem>
          <para>
            Install an XML menu file to <replaceable>sysconfdir</replaceable>/desktop/menus/applications-merged/ to add any submenus, if your desktop entries aren't already 
            included in some common categories.
          </para>
        </listitem>
        <listitem>
          <para>
            Install any directory entries needed for your submenus to <replaceable>datadir</replaceable>/desktop-directories/, taking care to namespace and validate
            the directory entries.
          </para>
        </listitem>
      </itemizedlist>
    </para>
    <para>
      Also, at least for a good long while, installing a directory hierarchy to
      the old GNOME/KDE specific locations such as /usr/share/applnk and
      /usr/share/gnome/apps should work. There are two ways to support 
      both the old and new menu systems at the same time:
      <itemizedlist>
        <listitem>
          <para>
            If you add a <varname>Categories</varname> line to the desktop
            entries in the legacy hierarchy, implementations of this
            specification will ignore their location in the legacy hierarchy,
            and arrange them according to <varname>Categories</varname> instead.
            This allows you to install a single desktop file that works in all
            cases, though on the down side it's in a legacy location.
          </para>
        </listitem>
        <listitem>
          <para>
            If you add the line <literal>OnlyShowIn=Old;</literal> to a desktop
            entry, then old legacy implementations that ignore
            <varname>OnlyShowIn</varname> will still show the desktop entry, but
            implementations of this specification will not. Thus you can 
            add an "<literal>OnlyShowIn=Old;</literal>" entry to the legacy 
            hierarchy, and a new-style desktop entry to 
            <replaceable>datadir</replaceable>/applications/, and still get 
            only one entry in the menus.
          </para>
        </listitem>
      </itemizedlist>
    </para>
  </appendix>
  <appendix id="implementation-notes">
    <title>Implementation notes</title>
    <sect1 id="menu-editing">
      <title>Menu editing</title>
      <para>
        To implement menu editing, the intent is that a per-user file is
        created.  The per-user file should specify a &lt;MergeFile&gt; with the
        system wide file, so that system changes are inherited.  When the user
        deletes a menu item, you add
        <literal>&lt;Exclude&gt;&lt;Filename&gt;foo.desktop&lt;/Filename&gt;&lt;/Exclude&gt;</literal>. If
        the user adds a menu item, you use
        <literal>&lt;Include&gt;&lt;Filename&gt;foo.desktop&lt;/Filename&gt;&lt;/Include&gt;</literal>.
      </para>
      <para>
        If the user moves a folder, you might try to use &lt;Move&gt; elements
        to represent that, but it's tricky. (Move A/B/C to D/E/F, then move D/E
        to D/G, note that D/E/F still contains A/B/C while only the original D/E
        was moved to D/G.) In order to move a folder, you have to "fix up"
        all moves that move things <emphasis>into</emphasis> the folder being
        moved to instead move things into the folder's new location.
      </para>
      <para>
        To delete a folder, simply append the &lt;Deleted&gt; element.
      </para>
      <para>
        Menu editors probably need to do some kind of consolidation/compression 
        to avoid an XML tree that grows infinitely over time.
      </para>
    </sect1>
  </appendix>
  <glossary><title>Glossary</title>
    <para>
      This glossary defines some of the terms used in this specification.
    </para>
      
    <glossentry id="term-desktop-entry"><glossterm>Desktop entry</glossterm>
      <glossdef>
        <para>
          A desktop entry is a file with a name ending in the ".desktop"
          extension which conforms to the <ulink
		  url="http://www.freedesktop.org/standards/desktop-entry-spec">desktop
          entry specification</ulink>. It describes a menu item, including 
          a name, an icon, and what to do when the item is selected.
          Desktop entries are also known as ".desktop files."
        </para>
      </glossdef>
    </glossentry>

    <glossentry id="term-desktop-file-id"><glossterm>Desktop-File Id</glossterm>
      <glossdef>
        <para>
          The id to identify a desktop entry with. 
          For example, if <filename>/usr/share/applications</filename> is
          specified as an &lt;AppDir&gt;, and <filename>/opt/ude</filename>
          as &lt;LegacyDir prefix="foo-"&gt;
          then 
          <filename>/usr/share/applications/foo/bar.desktop</filename>, 
          <filename>/usr/share/applications/foo-bar.desktop</filename>
          and
          <filename>/opt/ude/Settings/bar.desktop</filename> all have
          the same desktop-file id <literal>foo-bar.desktop</literal>
        </para>
      </glossdef>
    </glossentry>

    <glossentry id="term-directory-entry"><glossterm>Directory entry</glossterm>
      <glossdef>
        <para>
          A directory entry is a file with a name ending in the ".directory"
          extension which conforms to the <ulink
		  url="http://www.freedesktop.org/standards/desktop-entry-spec">desktop
          entry specification</ulink>. It describes gives a localized name and 
          an icon for a submenu.
          Directory entries are also known as ".directory files."
        </para>
      </glossdef>
    </glossentry>

    <glossentry id="term-menu-path"><glossterm>Menu path</glossterm>
      <glossdef>
        <para>
          A "menu path" is the path to a particular menu. Menu paths are 
          always "relative" so never start with a slash character. 
          The path to a menu is simply the &lt;Name&gt; of each parent 
          of the menu, followed by the &lt;Name&gt; of the menu itself.
          For example, "Foo/Bar/Baz" is a valid menu path.
        </para>
      </glossdef>
    </glossentry>

    <glossentry id="term-relative-path"><glossterm>Relative path</glossterm>
      <glossdef>
        <para>
          The canonical path to a directory entry, relative to the
          &lt;DirectoryDir&gt; containing the
          entry. For example, if <filename>/usr/share/desktop-directories</filename> is
          specified as an &lt;DirectoryDir&gt;, the relative path to
          <filename>/usr/share/desktop-directories/foo/bar.directory</filename> is
          <filename>foo/bar.directory</filename>.
        </para>
      </glossdef>
    </glossentry>
  </glossary>
</article>