This module is one of the standard `predicate' modules. It provides a consistent set of predicate_declarations. This predicate module is the module of choice if you are not interested in predicates on symbols, and you don't need the ?/0 any symbol operator.
The module only has a restricted set of predicate_declarations; most notably it lacks definitions for true/1 and therefore the use of the any symbol ?/0 operator is not allowed (and neither the corresponding complement ~/1 operator).
This predicate module is used internally for treating transducers temporarily as recognizers; e.g. if you want to determinize a transducer as if it were a recognizer by viewing each transition pair as an atomic unit.