[Gmsh] Elements & Physical entities

[Borek Patzak]

Hello,

I have a question concerning the way how physical entities are exported.
I would like to use the concept of physical entities to handle boundary 
conditions.
 From the documentation and my experiments it seems to me, that on 
output the mesh contains the elements associated to individual physical 
entities. My problem is following: if the physical entity is some part 
of boundary (curve in 2D or surface in 3D) of the whole domain, I need 
in some cases somehow to relate  this information to domain elements, 
not to the "elements" discretized on the boundary. In the case of square 
2D domain, where boundary condition is applied to one side, I need to 
pass this information to 2D elements, that have heir edge on this side.
1) Is there some way how to get this  information from mesher?
2) If not, one can reconstruct this information from a list of 
edge-elements generated for this side. Does such a tool already exists?

Thank you
Bob