Feel free to use this protocol in your own engines or interface. I only ask that if you call your engine or interface cxboard compliant that you be sure that it is. Contact the authors though the sourceforge website at http://xiangqi-engine.sourceforge.net to request additions or alterations to the protocol before altering it yourself. If you need alterations that are not being included in the protocol you may create derivative works but you must call them by a different name.
Please keep in mind that this protocol is a copyrighted work. We are asking very little from users; only what is needed to be sure compatability is retained. It is a sad world indeed if these requirements cannot be met.