An assembly document that is used to automate the placement of a group of parts and features.
A systems library document can consist of the following:
Complete subassembly documents
Part documents
Features that are associative children of one of the part documents
The parts and features are usually standard in nature and are typically used in many assemblies. Grouping them into one assembly document allows for quicker placement in another assembly.
After placement, the parts behave exactly the same as any parts in an assembly. The systems library assembly document is not placed in the assembly. It functions as a container to group the components, and speed the placement of the subassemblies, parts, and features.
You can also create systems library documents that contain only parts and no features.