NOT Operator
 
Syntax
  result = NOT numeric-expression
 
The logical-complement operator evaluates each bit in numeric-expression,
then sets the corresponding bit in the result according to the following
table:
              Bit in Expression         Bit in Result
                       1                       0
                       0                       1
This inverts the bit values of any variable. If an integer variable has
the value 0 (false), the variable becomes -1 (true), and vice-versa.