The .ERRB and .ERRNB directives test the given Text-Argument.
Syntax
.ERRB Text-Argument or .ERRNB Text-ArgumentRemarks
If Text-Argument is blank, the .ERRB directive produces an error. If Text-Argument is not blank, .ERRNB produces an error.
You can test for the existence of parameters by using these directives within macros.
In this example, the directives ensure that only one argument is passed to the macro. If no argument is passed to the macro, the .ERRB directive produces an error. If more than one argument is passed, the .ERRNB directive produces an error.
WORK MACRO REALARG,TESTARG .ERRB <REALARG> ;; Error if no parameters .ERRNB <TESTARG> ;; Error if more than one parameter . . . ENDM