<NOT> element is an access control operator that that reverses the result of a single nested rule or operator, meaning it is satisfied if and only if its child is not.
One (and only one) of the following elements can appear:
A single access rule to enforce.
A single regular expression access rule to enforce.
An operator for combining any number of rules or operators with a disjunction.
An operator for combining any number of rules or operators with a conjunction.
An operator for reversing the meaning of a single rule or operator.