logic.1
This source file contains all the words to perform logical operations and comparisons between items (other than strings).
true
( --- f1 )
This constant returns a true / -1 value.
false
( --- f1 )
This constant returns a false / 0 value.
and
( n1 n2 --- n3 )
This word performs a logical anding of the top two items of the parameter stack.