c/- All: In taking a holistic look at some of the work I do, I've come to realize a need for a "transparent" data type, and wondering whether or not it exists. As all of you would have experienced, any organization has such a representation of such a type; be it called: "Null value", "Missing value", "Fill value", "Infinity" , or whatever. What I am hoping for is support for such an representation, with existing containers and algorithms; such that if you perform any mathematical operation, (arithmetic, transcendental; inverse; anything really ...); that you get back the *same* object (ie. it passes transparently through any operation), and not raise any exception if you so choose. Example: missing_val == atan(missing_val) - missing_val; missing_val == 1 / missing_val; missing_val == missing_val + missing_val; missing_val == missing_val - missing_val; typedef std::vector<any_type> dVec; dVec some_vector; ... populate some_vector ... dVec::iterator = some_vector.find(missing_val); Boosters, do we have such a representation; is there value in having such a thing in Boost; is there a (simple) alternative work-around ?? All ideas and comments appreciated. Cheers, -- Manfred MetOcean Engineers