+.SH ATTRIBUTES
+.SS Multithreading (see pthreads(7))
+The
+.BR sigvec (),
+.BR sigblock (),
+.BR sigsetmask (),
+and
+.BR siggetmask ()
+functions are thread-safe.
+.LP
+The
+.BR sigmask ()
+macro is thread-safe.
+.SH VERSIONS
+Starting with version 2.21, the GNU C library no longer exports the
+.BR sigvec ()
+function as part of the ABI.
+(To ensure backward compatibility,
+the glibc symbol versioning scheme continues to export the interface
+to binaries linked against older versions of the library.)