SwNtfy Fn 0006H: Switcher Is Destroying a Session

  Expect: AX    0006H
          BX    ID of the session
          ES:DI addr of switcher's service-entry address
  Return: AX    0000H (you must return 0 in all cases)
    Info: Task switchers call this to let you know that a session is about
          to be destroyed.  It gives you a chance perform any cleanup
          needed to process the end of a session.

          When called, interrupts are enabled you may use all DOS fns.

       BX will contain the session ID of the session that is about to be
          destroyed. (Note: it need not be the current active session).

    ES:SI will contain the task switcher's service entry address.  Use this
          address if you need to call any task-switcher service fns.

  Return: AX=0000H you must return 0.  Tasks have not veto power here.

   Notes: You may get this call without first seeing a SwNtfyFn 0006H
          (session is being created).  That call is broadcasted when some
          task has vetoed the new session.  In that case, you may ignore
          this call.

See Also: Switcher Services and Notifications
          INT 2fH 4bxxH (switcher functions)