Hi Joachim One small note about Icl maps. I think would be useful to make interval_map::find()'s function accept any type comparable to map's key. For example, the key type is std::string and the user want to search using a 0-terminated string or a string defined as arbitrary pointer and a length. Then the user will have to allocate the temporary string only to pass it to interval_map::find() You may argue that the std::map works same way. But there is the difference. If I want to do the trick above, I can use boost::multi_index or at least instead of std::map<std::string, ValueT> I can define something like std::map<tuple<const char*, size_t>, tuple<std::string, ValueT>> with key's const char* and size_t pointing to the data hosted in value. This is not possible with interval_map, where the values can be joined