This can be one of the object types that are listed in uf_object_types.h
object_subtype
int
This can either be UF_all_subtype, or a proper subtype of the object type selected. This is ignored for UF_solid_type
solid_type
int
This is only meaningful when the object_type is UF_solid_type or UF_feature_type. In that case, this should be set to one of the solid type constants. This is ignored for UF_all_subtype
uf_object_types.h