There are TWO issues which prevent perfect round tripping of floats/doubles <-> strings. a) correct number of digits and correct rendering/round tripping of floating point values b) portable rendering of the variety of Nans. Both of these issues have been discussed extensively on this list - without any resolution. I would think that resolving these issues is very important and long overdue. On the other hand - I don't see the motivation for including concepts in the core language. Haven't we been able to implement concept checking with the current facilities of the library? It seems to me that the main problem these days with the C++ language these days is that its too hard to write a correct compiler for it. Making the core language fancier will only make this problem worse. While, the commitee is at it - how about re-visiting two-phase lookup. Apparently there are enough implementers skeptical about it that they've declined to implement it. (for good reason in my opinion). I believe this is related to the "export" feature - which has also failed to gain traction. So its seems to me that there are a number of issues more important/urgent than the ones currently being focused on. Robert Ramey