Environment functions do not create features, rather they are used to create a work environment, including datums. This group of functions includes:
Activate: Activate one object (open or closed) or deactivate all objects. This creates a work mode in which you establish the behavior of subsequent functions.
Plane: Create a datum plane. This plane will not be included as part geometry, but rather will act as a reference or as a plane for sketching.
Axis: Create a datum axis. This axis will not be included as part geometry, but rather will act as a reference within part and / or assembly documents.
UCS: Create coordinate systems. Every document contains a default UCS, this function is only needed to create new UCS's.