Reference

An origin. A reference carries a position and an orientation, and other objects hang off it.

What it is for

To give a group of things one place to be moved from. A pallet station is the usual example: the station's reference holds the container, its approach positions and its drop positions, so correcting the reference corrects the lot.

A cell built on references survives the real world. A cell built with everything in world coordinates has to be re-taught every time something is bumped.

Creating one

Add it, place it, then drag onto it whatever belongs to it. Its helper shows the three axes, which is worth leaving on while you build: an origin rotated 90° from what you assumed is very hard to see and very easy to check.

Moving a whole branch

Move the reference and everything under it moves. That is the whole point, and it is also the warning: check what is under a reference before you move it.