## 1.8 Acknowledgements

The development of XPCE was started by Anjo Anjewierden. The package was then called PCE. He designed and implemented version 1 and 2. Version 3 is the result of a joint effort by Anjo Anjewierden and Jan Wielemaker.

XPCE-4, offering support for X-windows and user-defined classes, has been implemented by Jan Wielemaker. The implementation of user-defined classes was initiated when Jan Wielemaker was guest at SERC (Software Engineering Research Centre). Gert Florijn has contributed in the initial discussions on user-defined classes. Frans Heeman has been the first user.

The interface to SICStus Prolog has been implemented in cooperation with Stefan Andersson and Mats Carlsson from SICS.

The interface to Quintus Prolog was initiated by Paul-Holmes Higgins. The project was realised by James Little, Mike Vines and Simon Heywood from AIIL.

Luca Passani has bothered us with many questions, but was so kind to organise this material and make it available to other XPCE programmers in the form of a FAQ.

Gertjan van Heijst has commented on XPCE as well as earlier drafts of this documents.

(X)PCE is used by many people. They have often been puzzled by bugs, incompatibilities with older versions, etc. We would like to thank them for their patience and remarks.