sacred
Reserved for the exclusive use of something (an extension of
the standard meaning). Often means that anyone may look at
the sacred object, but clobbering it will screw whatever it is
sacred to. The comment "Register 7 is sacred to the interrupt
handler" appearing in a program would be interpreted by a
hacker to mean that if any ▫other▫ part of the program changes
the contents of register 7, dire consequences are likely to
ensue.
[{Jargon File}]