Is there a way to "associate" an external property map to a name so that it can be retrieved from the graph? With a standard interior property, you can do: // Declare that you will be able to identify a property map by "vertex_data" namespace boost { enum vertex_data_t { vertex_data }; BOOST_INSTALL_PROPERTY(vertex, data); }; // Get the vertex_data property map from the graph typedef boost::property_map<Graph, boost::vertex_data_t>::type PropertyMapType; PropertyMapType propertyMap = get(boost::vertex_data, g); However, with the exterior properties, I can associate the property map with the nodes of the graph: typedef boost::property_map<GraphType, boost::vertex_index_t>::const_type indexMapType; indexMapType indexMap(get(boost::vertex_index, graph)); boost::vector_property_map<float, indexMapType> myMap(100, indexMap); but how would I then be able to, only having the graph object, get this map? That is, there was never any name, like "vertex_data" introduced in this case. Thanks, David