Hello, your library sounds interesting to me, even if I have some questions: 1) what requirements the enumeration type should satisfy? For example, am I obliged to declare 2's powers? such as enum my_enum { flag1 = 1, flag2 = 2, flag3 = 4, ..... }; 2) when you assign a value to a boost::flags<my_enum>, do you use my_enum constants? It seems that flag1 | flag2 is an int, thus how can you distinguish between flag1 | flag2 and another user provided integral constant. Do you overload the "bitwise or" to produce an intermediate object??? 3) I agree with you about the usefulness of such a library, since a compile time check will assure that whenever the code is actually executed, properties will be always in a sensible state (eliminating the annoying and error prone runtime validation). If the programmer consider every notable case, then a static checked flag will give us the same assurances which could give us a collection of methods, one for each particular flag combination. Best regards, Manuel Fiorelli