VMS Help CC, Messages, ENUM16BIT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 Message        <Context> the enumeration constant <name> is out of
                the range -32768 to 32767.  This might not be
                portable.

 Description    An enum constant is larger than can be represented in
                16 bits.  This would not be portable to a system with
                an int size of 16 bits.

 User Action    Be aware of this if you wish to port to a system with
                an int size of 16 bits.