It depends a lot on the PTIs on the day and what mood they're in [and you think I'm joking...].
Normally, however, it is roughly the following:
Feet shoulder width apart, knees bent at 90°. Fingers to temples, elbows to the front. All the way down until your shoulder blades hit the floor, all the way up until your elbows are on the tops of your knees. Feet held very lightly.