Op is the result of comparing the terms Term1 and Term2 . One of the currently defined atoms is Atom . Unifies HostName with the name of the host SICStus is running on. Stream is the current input stream. There is a recorded item in the internal database whose key is KeyTerm , the name of which is KeyName .
Module is a module currently in the system.
Atom Op is an operator type Type precedence Precedence . Stream is the current output stream. A user defined predicate is named Name , most general goal Head . There is a stream Stream associated with the file FileName and opened in mode Mode . The terms X and Y are different.