Hi, Take this code: #include <boost/assign/std.hpp> #include <boost/assign/list_of.hpp> #include <boost/assign/list_inserter.hpp> #include <map> #include <iostream> #include <string> using namespace std; using namespace boost::assign; const unsigned long USER = 0x0001; const unsigned long ADMINISTRATOR = 0x0004; const unsigned long ALL = USER + ADMINISTRATOR; typedef map<string, long> item_permissions_t; typedef map<string, item_permissions_t> module_permissions_t; int main() { map<string, module_permissions_t> permission_table = map_list_of ("Module1", map_list_of ("Item1", map_list_of ("Feature1", ALL) ("Feature2", ADMINISTRATOR) ) ("Item2", map_list_of ("Feature1", ALL) ("Feature2", ALL) ("Feature3", ADMINISTRATOR) ("Feature4", ADMINISTRATOR) ) ); cout << "modules: " << permission_table.size() << "\n"; cout << "items of module 'Module1': " << permission_table["Module1"].size() << "\n"; cout << "features of item 'Item2' of module 'Module1': " << permission_table["Module1"]["Item2"].size() << "\n"; cout << "permissions of feature 'Feature4' of item 'Item2' of " "module 'Module1': " << permission_table["Module1"]["Item2"]["Feature4"] << "\n"; } It compiles fine with VC 7.1. However g++ 3.3 and 3.4 (both on Linux) refuse to compile it. See the error message (excerpt): sample.cpp:36: instantiated from here /usr/include/c++/3.4/bits/stl_pair.h:90: error: call of overloaded `map(const boost::assign_detail::generic_list<std::pair<const char*, boost::assign_detail::generic_list<std::pair<const char*, long unsigned int> > > >&)' is ambiguous /usr/include/c++/3.4/bits/stl_map.h:166: note: candidates are: std::map<_Key, _Tp, _Compare, _Alloc>::map(const std::map<_Key, _Tp, _Compare, _Alloc>&) [with _Key = std::string, _Tp = item_permissions_t, _Compare = std::less<std::string>, _Alloc = std::allocator<std::pair<const std::string, item_permissions_t> >] /usr/include/c++/3.4/bits/stl_map.h:156: note: std::map<_Key, _Tp, _Compare, _Alloc>::map(const _Compare&, const typename std::_Rb_tree<_Key, std::pair<const _Key, _Tp>, std::_Select1st<std::pair<const _Key, _Tp> >, _Compare, _Alloc>::allocator_type&) [with _Key = std::string, _Tp = item_permissions_t, _Compare = std::less<std::string>, _Alloc = std::allocator<std::pair<const std::string, item_permissions_t> >] the command line is: g++-3.4 -I ../boost_1_32_0/ sample.cpp -o sample Any ideas of what is going on here? Regards, Josue Gomes