My wish is to be able to schedule the exterior and interior faces of walls INCLUDING wall ends. This would be another property of the wall which could be scheduled. It would not depend on the join condition or Location Line.
Almost every Building Department in North America requires a 'Spatial Separation' table. This shows the total exposed wall area, the total unprotected area (not fire rated) and a percentage of the two. This is required for each direction North, South, East and West.
Currently this is not possible to calculate in Revit. The only way is to draw Filled Regions and use Dynamo to calculate.