[Boost-users] [BGL][Graph][vertex_descriptor] how do I get my vertex_descriptor?

This is probably in the Graph doc / book somewhere, but after a few hours poking around didn't find it... I added a bunch of vertices, each with a "unique id" property that comes from our system. Then I want to add the edges. Given the "unique id" from our system for the From and To vertices of the edge, how do I convert those "unique ids" into vertex_descriptors that can be passed to add_edge? tx Andy