Wait at a boundary can be used in many scenarios like having good manners at house doors, stairs, and car doors.
Step 1: Start by shaping your dog to stay on 1 side of the boundary (I use a broom). Every time your dog approaches the boundary, click and treat (C/T) BEFORE he takes a step over the boundary. When the dog is reliably remaining on one side of the boundary you will be ready to introduce the cue, “wait”.
Step 2: When the dog comes to the boundary and stops say, “wait”, C/T.
Repeat this step 10 times until your dog is stopping when you say “wait”.
Step 3: Start using the cue “wait” in different scenarios (house and car doors, etc).
When you WANT them to cross the boundary, you can say “release” and then C/T for when he or she moves forward.
The more you practice the better your dog will be at waiting for you to release him or her to do another activity.