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.
