Thanks to all who responded. I've been building boxes using these
joints and hadn't a clue what they were called.

Double thanks to Swingman for the book ref - I'll see if the book is
available through my local library. Time for me to acquire a better
woodworking vocabulary...

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/solar.html