hi mathias, thanks for your response. but i think there is a misapprehension. i want something like http://www.boost.org/libs/multi_index/doc/tutorial/index.html. "indexed by shape" should meet my "index by name" and "indexed by number" should meet my "index by identifier", so i can get the associated element value either by locMap[nme] or by locMap[idf], or something like that :o) there are 3 sets, a name key set, a identifier key set and an element value set; and there mapping. in a bimap are only 2 sets, a key set and an element set, which can swapped. thats not what i want. best regards, daniel _____________________________________________________________________ Der WEB.DE SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen! http://smartsurfer.web.de/?mc=100071&distributionid=000000000066