How are the CAD models organized?
The Short Answer
The CAD files are layered using professional-grade naming conventions that help separate foundational items (ceiling, floors, walls, etc.) from architectural features (e.g. windows, doors, etc.), making it easier to edit the parts you care about most.
The Long Answer
The number at the beginning of the named layer (e.g. 1_, 2_, 3_) will help group together items of similar stature. The number behind the name (e.g. L1, L2) will indicate what level the item is located on (first floor or second floor).
Here's an example of a commonly layered model that has two floor levels:
Here is an example of disabling layers and how it can reveal/disable certain aspects:
In the above image, the ceiling layer is enabled as visible; in the image below the ceiling layer is disabled (or not visible).
For more information on how to use and manipulate layers within your CAD program, we encourage you to reach out to the customer support teams for the software you use directly (for example, AutoCAD or SketchUp)