1. Usage
Hold down the Scheme key while making a selection with the mouse. The usual Tioga selection modifiers work: control, shift, CTL-S, -X, -Z. ©The Scheme key¹ currently = ©Left Alt¹ in PCedar, and the shift lock in DCedar. Here is the coding:
Left => select form
Middle => select form's parent
Double Left => select form's parent's parent
Double Middle => select form's parent's parent's parent
Right => extend