ViewPlan.GetUnderlayTopLevel
Description:
Returns the element id of the level that defines the top of the underlay range.
Returns the element id of the level that defines the top of the underlay range.
public ElementId GetUnderlayTopLevel()
ElementId
If the underlay base level is a valid level, and this method returns InvalidElementId, then the underlay range is unbounded,
and consists of everything above the underlay base level.