## 2.1 Starting XPCE/Prolog

XPCE is distributed as a library on top of the hosting Prolog system. For use with SWI-Prolog, this library is auto-loaded as soon as one of its predicates (such as new/2) is accessed or it can be loaded explicitly using

    :- use_module(library(pce)).

In Unix XPCE/SWI-Prolog distribution the program xpce is a symbolic link to pl and causes the system to pull in and announce the XPCE library with the banner:

    % xpce
    XPCE 6.0.0, February 2002 for i686-gnu-linux-gnu and X11R6
    Copyright (C) 1993-2002 University of Amsterdam.
    XPCE comes with ABSOLUTELY NO WARRANTY. This is free software,
    and you are welcome to redistribute it under certain conditions.
    The host-language is SWI-Prolog version 5.0.0

    For HELP on prolog, please type help. or apropos(topic).
             on xpce, please type manpce.

    1 ?-

SWI-Prolog's prompt is ``<n> ?-'' where <n> is the history-number of the command. The banner indicates the XPCE version. The indicated version is 5.1 and the patch-level is 0.

On MS-Windows, Prolog programs are normally loaded and started by double-clicking a `..pl` file. XPCE, being a normal library, does not change this. Note that XPCE can only be used fully with the GUI-based plwin.exe. Using the the console-based plcon.exe program only the non-GUI functionality of XPCE is accessible.