Attachment point

These are the small green squares you see when you select a component in the window right under it's description. (In DSL they are brown and white)

Also called "APs" for short

Basically, an attachment point is where your component will be attached. It's very easy to get the thing : just select which attachment point you want to use. It will highlight and then you will be able to attach the component in different directions. Just try with a Z-tek: the two attachment points will allow you to place it horizontally or vertically (parallel or perpendicular). Most non-Power components have multiple attachment points. Thois is very useful.

A method to use wisely the round extenders attachment points