This feature was new to Inventor 2010 and with the next release on the way, I wanted to get this one in our blog. User Coordinate Systems in Inventor. I have found many interesting ways to implement this for customers over the year. In a single part you can use this to locate a new 0X,0Y,0Z, or just locate a specific connection point. Then in the assembly this works great for constraining parts together based on that known point instead of using three or more assembly constraints. This can be done easily using the Constraint Set constraint in the assembly environment. It allows you to quickly put components together based on mating UCS axis, and planes in a few clicks.