+@item
+This function is sometimes not declared in @code{<string.h>} on some platforms:
+glibc 2.8, OSF/1 5.1.
+@item
+The third argument is of type @code{int} instead of @code{size_t} on some
+platforms:
+AIX 5.1, OSF/1 5.1.
+@item
+When this function fails, it returns -1 and sets @code{errno}, instead of
+returning the error number, on some platforms:
+glibc 2.12 with @code{-D_POSIX_C_SOURCE=200112L}, AIX 6.1, OSF/1 5.1.
+@item
+This function does not support the error values that are specified by POSIX
+but not defined by the system, on some platforms:
+OpenBSD 4.0, OSF/1 5.1, NonStop Kernel, Cygwin 1.5.x.
+@item
+This function always fails when the third argument is less than 80 on some
+platforms:
+HP-UX 11.31.
+@item
+When the buffer is too small, this function does not fail, but instead
+truncates the result and returns 0 on some platforms:
+OSF/1 5.1.
+@end itemize
+
+Portability problems not fixed by Gnulib:
+@itemize
+@item
+When the buffer is too small, this function does not fail, but instead
+truncates the result and returns 0 on some platforms:
+AIX 6.1.