5 POSIX specification: @url{http://www.opengroup.org/susv3xsh/assert.html}
9 Portability problems fixed by Gnulib:
13 Portability problems not fixed by Gnulib:
17 Extension: Gnulib offers a module @code{assert} that allows the installer to
18 disable assertions through a @samp{configure} option: @samp{--disable-assert}.