The value BOOL is one of the 3 kinds of value (data types) in ITP. This means that a variable can be declared as a BOOL. It also means that a database field value, as retrieved by ITP, can be of type BOOL.
A BOOL variable can contain the value TRUE or the value FALSE, and nothing else. BOOL variables are typically used in control statements like IF, WHILE and REPEAT. The default value of a BOOL is FALSE.