Joaquín, thanks so much for a wonderful library. I was wondering why there is no constructor that simply takes an allocator. This would make multi_index behave more like STD Library containers, which would aid me in allowing flexible storage options for generic algorithms. Is there a technical hurdle that makes this difficult to do? You currently provide: explicit multi_index_container( const ctor_args_list& args_list=ctor_args_list(), const allocator_type& al=allocator_type()); template<typename InputIterator> multi_index_container( InputIterator first,InputIterator last, const ctor_args_list& args_list=ctor_args_list(), const allocator_type& al=allocator_type()); Is it possible to also provide: explicit multi_index_container( const allocator_type& al=allocator_type()); ? Thanks again! --Michael Fawcett