ERRIFxx          Conditional error directives                       Directive

  Force an error to occur if expression is true (non-zero). The optional
  message parameter will display as part of the error message. These
  directives are available in both Ideal and MASM mode.

  ERRIF expression ["message"]      Error if expression is true
  ERRIF1 ["message"]                Force error on pass 1
  ERRIF2 ["message"]                Force error on pass 2
  ERRIFB argument ["message"]       Error if argument is blank (empty)
  ERRIFDEF symbol ["message"]       Error if symbol is defined
  ERRIFDIF arg1,arg2 ["message"]    Error if args different (case-sensitive)
  ERRIFDIFI arg1,arg2 ["message"]   Error if args different (case-ignore)
  ERRIFE expression ["message"]     Error if expression is false (0)
  ERRIFIDN arg1,arg2 ["message"]    Error if args identical (case-sensitive)
  ERRIFIDNI arg1,arg2 ["message"]   Error if args identical (case-ignore)
  ERRIFNB argument ["message"]      Error if argument is not blank
  ERRIFNDEF symbol ["message"]      Error if symbol is not defined

  Examples:     ERRIFNDEF foo "foo not defined"
                ERRIFB <SegReg> "Need segment register"