The easy answer is that all the info is held in the Drawing. The centerlines hold the xdata, just like steel.

NOW, you can do a live DB for Plant (piping) and Steel that you can querry as well. This is optional, and is more of a dump from the drawing. You can update certain fields from the DB to the drawing.

If you want Len, you can shoot me your contact info and I can give you a call to cover some more of this if you would like.

KP