-
-You should include Gnulib-provided headers before system headers,
-so that Gnulib-provided headers can adjust how a system header
-behaves.
+Also, on some platforms macros like @samp{_FILE_OFFSET_BITS} and
+@samp{_GNU_SOURCE} may be ineffective, or may have only a limited
+effect, if defined after the first system header file is included.