[CONNECT C#] Grid created by Grid Manager


I am trying to access the grid properties (grid lines, coordinates, orientation, etc.) of a OpenBuildings Designer model from a c# addin. I can see from the XML export that the used EC schema should be StructuralModelingComponents.06.00.

When I ask the DgnECManager for discover-able schemas, it doesn´t include that schema though.

List<string> schemas = Enumerable.ToList(manager.DiscoverSchemas(Session.Instance.GetActiveDgnFile(), ReferencedModelScopeOption.All, true));

I also tried

FindInstancesScope scope = FindInstancesScope.CreateScope(Session.Instance.GetActiveDgnFile(), new FindInstancesScopeOption(DgnECHostType.All, true));
IECSchema schema = manager.LocateSchemaInScope(scope, "StructuralModelingComponents", 6, 0, SchemaMatchType.Latest);

but with no success. 

The IntegratedStructuralModel schema wouldn´t work either.

Are grid lines somehow not part of the model or should I look in a different schema? 

Might there be a different way to access grids? 

See also https://www.itwinjs.org/bis/domains/processphysical.ecschema/#ismcartesiangrid for reference.