4.2.2 Types of Predicates Supplied with SICStus Prolog

Certain predicates are predefined by the Prolog system. Most of these cannot be changed or retracted. Such predicates are called built-in predicates.

Other predicates can be modified or totally redefined. These are the hook predicates used e.g. in term expansion, the foreign language interface, file name resolution, printing, message handling, and query handling.