Hi Wolfgang,
Well, documenting everything would take too much time I am afraid, but you can see how everything works by following the high-to-low level implementation. For setting an order, see first the code for DBSetOrder(), as you can see it simply calls VoDb.OrdSetFocus(). VoDb inherits from CoreDb, and there you can find the method OrdSetFocus() defined, in file XSharp.Core\RDD\CoreDb.prg. Just use the same code in your custom class (with any adjustments you like of course) and it whould be fine! Same for everything else that you need to implement...