When insert an xref, how to make sure the insertion point is the special point of the xref drawing?

Issue: In CAD,When insert a DWG as external reference to the drawing, we drag the xref and specify the insertion point in the drawing, generally we are grabbing the (0,0) point of the xref, but what if we want to grab a special point of xref and insert it right to the special position in the drawing?  

Solution: define the base point in the xref drawing, so that this base point becomes the insertion point. Open the drawing which will be used as external reference, use command INSBASE or Base, then pick the special point that you want it to be insertion point.