Martin, I did a simple search through the Boost website, and on http://www.boost.org/libs/graph/doc/using_adjacency_list.htm, I found this: You can also use enum's instead of struct's to create tag types. Create an enum type for each property. The first part of the name of the enum type must be edge, vertex, or graph followed by an underscore, with a _t at the end. Inside the enum, define a value with the same name minus the _t. Then invoke the BOOST_INSTALL_PROPERTY macro. enum edge_myflow_t { edge_myflow }; enum edge_mycapacity_t { edge_mycapacity }; namespace boost { BOOST_INSTALL_PROPERTY(edge, myflow); BOOST_INSTALL_PROPERTY(edge, mycapacity); } compared to:

namespace boost{ enum vertex_xx_t { vertex_xx = 1111}; BOOST_INSTALL_PROPERTY(vertex,vertex_xx); }

which means it should be:

enum vertex_xx_t { vertex_xx = 1111}; namespace boost{ BOOST_INSTALL_PROPERTY(vertex,xx); }

Dale