NAME
        GoodID -- test if an identifier follows the IFF 85 specification. (V36)

   SYNOPSIS
        isok = GoodID(id);
        D0            D0

        long goodid(long);

   FUNCTION
        Tests the given longword identifier to see if it meets all the EA IFF
        85 specifications for a chunk ID. If so, it returns non-zero,
        otherwise 0.

   INPUTS
        id - potential 32 bit identifier.

   RESULT
        isok - non-zero if this is a valid ID, 0 otherwise.

   SEE ALSO
        goodtype()