/mx       Makes public and external symbols (globals) case-sensitive

          The /mx option tells Turbo Assembler to treat only external and
          public symbols as case-sensitive. All other symbols used (within
          the source file) are treated as uppercase.

          You should use this directive when you call routines in other
          modules that were compiled or assembled so that case-sensitivity
          is preserved; for example, modules compiled by Borland's line of
          C++ compilers.