Excellant! If I add it, it gives it a friendly place to live and as you develope same, we can just continue the version thing. It might also get me to get back into things like various conversions (english to algebraic for instance) at any rate it seems like an interesting piece of reasearch. Have you thought about black using a minor key with white playing a compatible major? Tempo on forced moves could be automagically distinguished from otherwise and similar such. Lots of canvas, room for much embroidery!!