Connection points can be placed anywhere on most nodes. Each connection point defines a location in addition to the center point where a path can be attached. When attaching a path to a node, the endpoint snaps to the nearest connection point, or automatically creates a new one if you choose.

Connection points do not normally print with the diagram, but you can choose to have them marked as black dots if required.

There are a number of convenient methods for adding connection points to a symbol:

Add connection points from the connection point dialog box and choose special behaviors for each point.
Use Connection Point Mode to manipulate connection points on the figures in your diagram using the mouse. Add, move, and delete connection points in place.
For greatest convenience, have connection points added automatically on a node wherever you click to attach. There are two ways to accomplish this (1) by using click point attach mode, or (2) by holding SHIFT while connecting in the usual way.