.ERRNZ           Error If True                                 MASM Directive

  .ERRNZ expression

    Forces a fatal error if expression is true (nonzero).

       Notes:     Expression must resolve to an absolute value and not
                  contain a forward reference.

                  The error message that may be generated by this
                  directive is 'Forced error - expression not equal 0',
                  which is error number 91.

                  If an error is generated, the object module is deleted
                  and the assembler exits with an exit code of 7.