Finding dependencies

I found a discussion on how dependencies are defined (hierarchical vs flat) in the archive. Sounds like the discussion was incomplete. Regardless of which method is used is there any tool that will walk the Portfile hierarchy to list all the dependencies? port deps <project/port name> will list the dependencies for the port, but it does not list the dependencies of the dependencies. My problem is that xmlto is a dependencies to some project that I am building but I cannot get xmlto to build and would like to remove it from the port that is causing it to build, however, I cannot figure out what project that is. Michael