Hi, Some thoughts on design/naming after reading docs of indexed_set (version 9). I've not tried compiling anything yet. 1. The naming here seems redundant: employee_set::nth_index_type<1>::type employee_set::index_type<name>::type Can't the "::type" bit be dropped"? Or the _type, e.g. employee_set::nth_index<1>::type employee_set::index<name>::type 2. Do tags have to be structs? struct name{}; ... non_unique<tag<name>,member<employee,std::string,&employee::name> ... employee_set::index_type<name>::type While it looks okay in tutorial examples, I can see not wanting that in the main namespace in a real program. But then having to use a namespace each time I use the tag will be make it a bit ugly: non_unique<tag<tags::name>,member<employee,std::string,&employee::name> ... employee_set::index_type<tags::name>::type If it was a string instead is it less efficient (or maybe it does not compile)? non_unique<tag<"name">,member<employee,std::string,&employee::name> ... employee_set::index_type<"name">::type 3. I think the compose_key example will be needed enough that it should be part of the main library. 4. I think some macros would be useful to enhance readability (rather than just to handle compiler incompatibilities as currently). I'll see what I come up with as I try to use the library. Darren