ADDRSUBCONST

Message        <Context> accepting the expression "<expr>" as a
               constant is a language extension.

Description    In many cases HP C accepts the subtraction of two
               addresses within the same array or struct/union as a
               constant.  The C standard does not consider such an
               expression to be a constant.  Therefore, this program
               does not conform to the standard and may be rejected
               by other compilers.

User Action    Change the expression to be a constant.