.ERRNB           Error If String Is Not Blank                  MASM Directive

  .ERRNB    <string>

    Forces a fatal error if string is not blank.

       Notes:     Note that the angle brackets, <>, are required around
                  the string.  The string can be any name, number, or
                  expression.

                  The error message that may be generated by this
                  directive is 'Forced error - string not blank', which is
                  error number 95.

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

                  .ERRB and .ERRNB are usually used to detect the presence
                  or absence of parameters in a macro.