I am trying to combine a stratigraphic model that has a number of aquifers with T-PROGS model. I decided to use HGUID to specify the material in the stratigraphic model and SoilID to specify the material in T-PROGS simulations. Do I have to define material for all SoilIDs and all HGUIDs? e.g. SoilIDs ====== Clay Silt Sand Gravel Peat Silty sand HGUIDs for ======== Aquifer 1 Aquifer 1 Aquifer 2 Aquifer 3 Aquifer 4 Aquifer 5 I'll be appreciative for any ideas on how to handle this situation. Thanks