12:44 Nov 3, 2011 

Thanks both, it´s good to have some second opinions! Thanks for the link, Sandra, I hadn´t come across that website yet either.

11:18 Nov 3, 2011 

I think you have made a good educated guess and agree with Philippa's suggestion of overlay too.
Here's a website that may be worth a look. http://www.agnelle.com/
The English translation is so-so IMHO but the French may be of interest or help.

11:04 Nov 3, 2011 

No, it doesn't seem to exist, but I think you're right about "overlap": it's a logical conclusion when you look at some of the meanings of "chape". You could also try "overlay".