+ </item>
+ <item>The XSI extension to <prgn>kill</prgn> allowing <tt>kill
+ -<var>signal</var></tt>, where <var>signal</var> is either
+ the name of a signal or one of the numeric signals listed in
+ the XSI extension (0, 1, 2, 3, 6, 9, 14, and 15), must be
+ supported if <prgn>kill</prgn> is implemented as a shell
+ built-in.
+ </item>
+ <item>The XSI extension to <prgn>trap</prgn> allowing numeric
+ signals must be supported. In addition to the signal
+ numbers listed in the extension, which are the same as for
+ <prgn>kill<prgn> above, 13 (SIGPIPE) must be allowed.
+ </item>