All ZW3D objects created at the Object Level (e.g., Parts/Assemblies, Drawing Packets, Drawing Sheets, Sketches and CAM Plans, etc.) are all referred to as root objects because they are top-level objects in the ZW3D hierarchy. Multiple root objects can be stored in a single ZW3D file.
Drawing Sheets can also be root objects (e.g., Root Drawing Sheets) as well as children of drawing packets. Sketches can also be root objects (e.g., Root Sketches) as well as children of any part (i.e., root part or any other component in an assembly).
Root objects can be create/edited using the Insert Menu, the default Object Editor Menu, and the ZW3D Object Manager. Root objects are created in and activated from the active file.
What you Should Know about Root Objects
The original design of ZW3D CAD/CAM called for multiple root objects (e.g. Part, Sheet, and Plan) per file. It also called for object instancing in assemblies, plans and sheets to be physical path and database file independent -- to accommodate relocation of an object from one file or directory to another. Therefore, if ZW3D cannot find a root object in its original parent file, it will search all files within the scope of the current directory, installation directories and "Search Paths". The "Search Paths" are searched in the order they are listed in "paths" (see
File > Search Paths).
In ZW3D, the object is "king", not the file it resides in. That is a key instruction as a new user of ZW3D. You should name parts, drawings, sheets and plans uniquely. You should never use the same name for two different objects, even if those objects are located in different directories. If you wish to version an object without changing its name, you should use ZW3D PDM.
To help new users avoid confusion, ZW3D displays a message when an object is automatically picked up from a file with a different name than the original file. However, it will not detect cases where the object is found in a file with the same name, but located in a different directory, because physical paths are not stored in the ZW3D product schema. Again, that is by design, so that the schema has a degree of independence from physical location. It is mapped onto the file system via "paths." It makes the objects more transportable, but requires that they be named uniquely.
Note that physical paths ARE stored in the part history for non-native files imported into ZW3D. If you wish for these files to travel with an object, they can be embedded in the part with the Link Manager.