EXIT (XP)

Quits the CMD.EXE program (command interpreter) or the current batch
script.

EXIT [/B] [exitCode]

  /B          specifies to exit the current batch script instead of
              CMD.EXE.  If executed from outside a batch script, it
              will quit CMD.EXE

  exitCode    specifies a numeric number.  if /B is specified, sets
              ERRORLEVEL that number.  If quitting CMD.EXE, sets the process
              exit code with that number.