o Are the names 'binary_int' and 'binary_nibble' good names? Pavel Vozenilek, who has very kindly been my Boost mentor, suggests 'bits' and 'nibble' may be better names.

"nibble" sounds like taking a small bite, and AFAIK, that's precisely why it's called that! But in computing, bite is spelled byte, and similarly, four binary bits make up a nybble (also using a 'y'). At least, AFAIK all my computing magazines from 20 years ago (back when nybbles were less unimportant :-) used this spelling; they were printed in the USA. q.v. http://www.jargon.net/jargonfile/n/nybble.html http://www.geocities.com/oosterwal/puzzle/nybbleq.html but http://en.wikipedia.org/wiki/Nybble forwards to nibble, so I imagine that nibble must be common in some circles. On to your main question: int refers to the acceptable range (short int <= int <= long int), so I think binary_int isn't quite what we're looking for. After trying out a few possibilities, I like the look of nybbles<0011,1010,1100,0100> best. Dave