International Wheelchair Basketball Federation Presents Classification Video
From Wheelchair Basketball Canada website:
The International Wheelchair Basketball Federation (IWBF) has launched a new video entitled Introduction to the IWBF Player Classification System. The video is designed to be a international classification resource and it is available in English, French, Spanish and Portuguese.
The classification of wheelchair basketball players has evolved significantly over the past 20 years. No longer is it necessary to individually examine each player in a medical room. 
Players are now classified in their playing environment, on the basketball court and in their playing chair. This enables the classifier to assess each player, as they will be when taking part in actual competitions.
You can find the video here.
About Classification
Classification is the process by which a team's total functional potential on the court is leveled off with respect to its opponent. It is a functional evaluation taking into consideration each player's ability to perform skills specific to the sport of wheelchair basketball; wheeling, dribbling, passing, reaction to contact, shooting, rebounding.
In Canada, classifications are closely based on the international classification system and range from 0.5 to 4.5. Lower class athletes are more limited in their functional skills. Athletes assigned higher classes have few if any limitations. The total number of points on the court assigned for each of the five players may not exceed 14 points at any one time in most divisions.
For more information, please visit the [Classification] section of Wheelchair Basketball Canada website or www.iwbf.org.