"REXXUTIL" was the first documentation available about the setup strings for WPS objects. It's now a little bit out of date but all setup strings mentioned in this document are of course also useful for example in OS/2 WARP.
So if you only want to setup some program icons or something like that this document contains all you must know for it.
(For a complete list of setup Strings see REXX Reference Summary Handbook or OS/2 2.11 Power Techniques).