A quick search also reveals that you can pick between three forms of wheelchair assistance .....
Service 1 (WCHR)
Customer requires assistance to and from the gate, but does not require any special assistance onboard to move around, including use of the onboard wheelchair.
Note: this service option assists customers to the gate; it assumes that the customer can make their own way to the aircraft either by the jetty or on the passenger coach. Service may not be provided on a 1:1 basis.
Service 2 (WCHS)
Customer requires assistance to and from the aircraft gate and assistance with stairs if aircraft is off stand. They do not require assistance onboard to move around, including use of the onboard wheelchair.
Service 3 (WCHC)
Customer requires assistance to and from the aircraft and also needs use of the onboard wheelchair to move around the cabin.
Note: if the customer is travelling on their own - please check they have enough upper body strength to be able to lift them selves onto the onboard wheelchair.