PBMake runs from a batch file, because it rewrites the batch file
      on the fly, and then executes it. Once the batch file is written,
      PBMake is done executing, and the batch file takes over.

      MAKE.BAT kicks off the process by calling PBMake in the second
      line. PBMake then reads in your script, determines what it needs
      to do, and rewrites MAKE.BAT.

      Once you see the actual process of compiling and linking, you are
      seeing the batch file, MAKE.BAT, in action.

      You can get an education about this by typing:

      MAKE MYPROG /ALL

      and then viewing the contents of MAKE.BAT. You will see that
      MAKE.BAT contains everything it takes to build your entire
      project. Now, once everything is freshly built, run the same
      command again, but without the /ALL command.

      PBMake will see that nothing needs to be done, and will rewrite
      MAKE.BAT to reflect this. Now, veiw MAKE.BAT again.

      See the difference?

      PBMake makes use of a little known trick in DOS. Batch files have
      no idea what is in them even after they are running. DOS keeps
      track of what the last line was that executed, and when that
      process is finished, DOS moves to that line + 1. PBMake has
      rewritten lines 3 - n with the new process. DOS is fooled and
      executes the new batch lines. The result is no memory overhead.

      This is the basis for many network and hard disk menuing systems.