Not (')
Inverts the truth value of the boolean operand.
Details
The Not operator inverts the truth value of the boolean operand. If the operand is TRUE (1), Not gives it a value of FALSE (0). If the operand is FALSE (0), Not gives it a value of TRUE (1).
Examples
For example, the following statements produce a result of FALSE (0):
SET x=0
WRITE x
While the following statements produces a result of TRUE (1).
SET x=0
WRITE 'x
The Not operator combined with a comparison operator inverts the sense of the comparison. For example, the following statement displays a result of FALSE (0):
WRITE 3>5
But, the following statement displays a result of TRUE (1):
WRITE 3'>5