ECLiPSe (ECRC Common Logic Programming System) is a Prolog based system whose aim is to serve as a platform for integrating various logic programming extensions. The kernel of ECLiPSe is an efficient implementation of standard (Edinburgh-like) Prolog as described in basic Prolog texts [6]. It is built around an incremental compiler which compiles the Prolog source into WAM-like code [23], and an emulator of this abstract code.