Syntax:  SET MENU LABEL menu_label tpu_command mnemonic_character

  Modifies an existing menu label.

  This command lets you change the text processing utility (TPU) code
  that is bound to a menu label.  You can also modify the character
  used as a mnemonic for the label.

  RELATED COMMANDS:

     DELETE MENU commands        SAVE SECTION
     NEW MENU commands           SET MENU commands