DEFPLUS MODULE - defplus.pm
The defplus module allows extra information to be appended to an existing macro. Its file name is defplus.pm.

The defplus module allows further things to be appended to existing macros. The module implements one keyword:

#defplus macro definition...
    The #defplus keyword has the same syntax as #define, the only difference being if the macro is already defined then definition is appended to the existing definition of the macro. If the macro is undefined then #defplus behaves in exactly the same way as #define.