+@item
+The macros @code{SA_RESETHAND} and @code{SA_RESTART} are not defined
+on some platforms:
+NonStop.
+@item
+The type @code{sighandler_t} (a GNU extension) is not defined on most non-glibc
+platforms:
+MacOS X 10.5, FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, AIX 5.1, HP-UX 11,
+IRIX 6.5, OSF/1 5.1, Solaris 11 2010-11, Cygwin, mingw, MSVC 9, Interix 3.5, BeOS.