@item
This header file is missing on some platforms: msvc.
@item
-The SEEK_* macros are not defined in this file on some platforms: mingw.
+The SEEK_* macros are not defined in this file on some platforms:
+mingw.
+@item
+The *_FILENO macros are not defined in this file on some platforms:
+OS/2 EMX, mingw.
@item
The @code{_exit} function is not declared in this file on some platforms:
mingw.
+
+@item
+Some platforms provide a @code{NULL} macro that cannot be used in arbitrary
+expressions:
+NetBSD 5.0
@end itemize
Portability problems not fixed by Gnulib: