Simplify the following text for a Grade 9 native English-speaking person.
Original: There were also events for wheelchair tennis players , they competed in two categories : Paraplegic players where men and women play in separate competitions and a category for Quadriplegic 's , shortened to Quads and is a mixed event . These competitions are part of the NEC tour , under the Grand Slam category .
Simplified: There was also events for wheelchair tennis players ( they competed in three categories : men , women and quadipedic ) as part of the NEC tour , under the Grand Slam group .