<item>
<tt><ref id="alias" name="unalias"></tt> [ * | <em/key/ ... ]
<item>
+<tt><ref id="alternates" name="alternates"></tt> <em/regexp/ [ <em/regexp/ ... ]
+<item>
+<tt><ref id="alternates" name="unalternates"></tt> [ * | <em/regexp/ ... ]
+<item>
<tt><ref id="alternative_order" name="alternative_order"></tt> <em/mimetype/ [ <em/mimetype/ ... ]
<item>
<tt><ref id="alternative_order" name="unalternative_order"></tt> <em/mimetype/ [ <em/mimetype/ ... ]