* Undefined behavior --- behavior, upon use of a nonportabl…
* Undefined behavior --- behavior, upon use of a nonportable or erroneous program construct, of erroneous data, or of indeterminately-valued objects, for which the Standard imposes no requirements.
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Permissible undefined behavior ranges from ignoring the situation completely with unpredictable results, to behaving during translation or program execution in a documented manner characteristic of the environment
(with or without the issuance of a diagnostic message), to terminating a translation or execution (with the issuance of a diagnostic message).
Undefined behavior is otherwise indicated in this Standard by the words ``undefined behavior'' or by the omission of any explicit definition of behavior. There is no difference in emphasis among these three; they all describe ``behavior that is undefined''
If a ``shall'' or ``shall not'' requirement that appears outside of a constraint is violated, the behavior is undefined.