[Boost-users] GRAPHVIZ_DIRECTED macro definition?

Hi, In the file .../libs/graph/src/graphviz_parser.y we have the following: #ifndef GRAPHVIZ_DIRECTED #error Need to define the GRAPHVIZ_DIRECTED macro to either 0 or 1 #endif I couldn't locate the definition for the above macro in my boost installation. Do we need to define it explicitly, or am I missing some file(s)? Thanks, Soumitra