DOS Fn 4dH: Get Program Exit Code

                                                         Compatibility: 2.0+ 
 Expects: AH    4dH
 Returns: AL    exit code▲ of last process to terminate
          AH    Exit method: 0 = normal termination
                             1 = Ctrl-Break termination  INT 23H
                             2 = termination via critical error  INT 24H
                             3 = termination via Fn 31H KEEP
    Info: Returns the exit code of the most-recently terminated process.
          The exit code is set when a program calls DOS Fn 4cH or 31H.

          This function returns valid information only once for each
          terminating process.

See Also: Process Control Functions
          Program Startup & Exit
          DOS Functions