IFIDN            Assemble If Arguments Are Identical           MASM Directive

  IFIDN <argument1>,<argument2>
  statements
  [ELSE
  statements]
  ENDIF

    Initiates a conditional block, causing assembly of statements up to
    the optional ELSE directive, provided the two arguments (which may be
    names, numbers, or expressions) match character for character.

       Notes:     The comparison is case-sensitive.

                  The angle brackets must be included and the 2 arguments
                  must be separated by a comma.

                  This directive is often used to test parameters passed
                  to macro definitions.