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1.                 From The Free On-line Dictionary of Computing (19 January 2023):
                   
   
   
                   
                     
   sacred
      <jargon> Reserved for exclusive use by something.  The term
      might mean only writable by whatever it is sacred to.
      For example, "Register 7 is sacred to the interrupt handler"
      would mean that if any other code changed the contents of
      register 7, dire consequences would ensue.
      [Jargon File]
      (2002-12-30)