A. Apply the handbrake
A. Apply the handbrake
B. Put the car into reverse gear if it has manual transmission
C. Turn the wheels towards the kerb
D. Run the front and back wheels against the kerb
E. Turn the wheels away from the kerb
This section of the Road Code has been around for years. The reason you would do all of this is that older style handbrakes (which are the first line of resistance, and hold the rear wheels) have a tendency to slightly loosen after being pulled on if the mechanism was hot and then cools, so if you didn't have the handbrake on hard enough, the vehicle could roll forward in a car with a manual gearbox.
In a manual car, putting the car into reverse is the second line of defence because it provides a lot of resistance because the engine will not want to turn over backwards, which is what will happen if the car starts to roll forwards. The opposite is true if you park uphill.
In an automatic car, P (park) prevents the car from rolling forward.
This video shows how a mechanical hand brake (or 'parking brake') works.
Modern cars have hydraulic hand brakes which provide the optimal amount of force.
If the car does roll forward, pointing the wheels towards the kerb means that the car will roll into the kerb and, as long as it doesn't have too much speed, the kerb will stop it. If the wheels are angled outwards the car will turn towards the traffic lanes creating a risk to other road users.