MASM51           Enable MASM 5.1 enhancements                       Directive

  MASM51                                ; Superseded by VERSION

    This directive enables a number of MASM 5.1 enhancements that are
    not usually available in TASM. These enhancemnts are:

                o  You can use the SUBSTR, CATSTR, SIZESTR, and INSTR
                   macro directives.
                o  Long lines can be continued with a backslash (\).
                o  Support of the :: directive.


    If you also give the QUIRKS directive, these further enhancements are
    added:
                o  You can define local labels with @@ and refer to them
                   with @F or @B.
                o  You can redefine variables inside PROCs.
                o  Extended model PROCs become PUBLIC.