?DEBUG           Brief debug information (undocumented)

  ?DEBUG L nn

    ?DEBUG causes Turbo Assembler to place line-number information in the
    object file. This lets Borland's stand-alone debugger, Turbo Debugger,
    display the current location in your source code. It is an alternative
    to the /zd command line switch if assembly speed and memory usage are
    important.

    Note:   You cannot use ?DEBUG in a module that is assembled with the
            /zd or /zi command line option.

    Example:       ; ...
                   jz   @@skip
            @@tricky_stuff:
                   ?DEBUG L 45          ; I.e. line 45 in source text
                   ; ...