Define optical properties of materials in gdml files

Hello

I want to add the optical properties of materials in gdml file. is it possible?? how can i add this properties to gdml file??

Hi, you find a simple GDML sample provided in one of the GDML examples in Geant4…
see opticalsurfaces.gdml in examples/extended/persistency/gdml/G01.

Cheers, Gabriele