Finding a Layout wherein a ViewPort lives

[PellaCAD]

Here's another new and interesting ViewPort related question...

How do we determine the source layout of a viewport? (The layout upon which the object viewport resides.)

What method tells us this info?

(Is ViewPort theory something that Autodesk didn't finish?)

(Is there a book, source, god or guru that can help with understanding and using ViewPorts and PViewPorts?)

[RobertB]

All objects in AutoCAD know their container's object ID. The .NET object model for the Entity class has a BlockId property which is the ID of the block table record where the entity resides.