+@item
+@code{struct sigaction} lacks the @code{sa_sigaction} member on some
+platforms:
+Irix 5.3, Interix 3.5.
+@item
+The signal @code{SIGPIPE} is not defined on some platforms:
+mingw.
+@item
+The macro @code{SA_NODEFER} is not defined on some platforms:
+Interix 3.5.