Hi Robert
The iWD Capture Point stop operation is stopping a running intreaction from further processing similar to a Hold request.
If you are looking for more information on the iWD 8.x integrated capture points they are actually part of Interaction Server so you should refer to the eServices 8.1.4 Integrated Capture Points Guide found in the eServices documentation.
I do not believe there is a listing anywhere of all the possible error codes and their descriptions but the documentation referenced should have some examples.
Thanks
Troy Mortimer
Genesys Customer Care