... NOT log_exp ...
The negation of a logical expression log_exp with NOT, forms a new logical expression, which is false, if the logical expression log_exp is true and vice versa.
The Boolean operator NOT must not be confused with the addition NOT on BETWEEN, IS and IN. The following syntax is possible:
... NOT operand NOT IN seltab ...
The first NOT is a Boolean operator which negates a logical expression with the addition NOT. The second NOT is an addition in a logical expression. This is made clear with the brackets around the logical expression:
... NOT ( operand NOT IN seltab ) ...