Nand is a logical "not and" operator which can be used in an expression.  It produces the opposite of the logical negation of the "and" operator.

 

The expression "A nand B" returns True when (1) A is false, or (2) B is false, or (3) both A and B are false.

 

LRM

    7.2

 

See also

image\diamond.gif  Object, Data Types and Operators