The Set Insertion Origin command
allows you to select a point on a drawing as the insertion origin. The system shows the current point and a 'rubber-band' line is attached from it to the cursor point.
You can use any of the snaps and input options
to do this. This is the point that the cursor will be attached to when placing the drawing as a symbol onto another drawing.
You can also add further Insertion Points
at key positions, these can be used as alternative points when inserting the symbol.