2.2 Placing the checkpoints
OK, right after that "// Laps, checkpoints etc"-note is a value, which means the number of checkpoints in the track. After that value there is:
// Checkpoint #1 , just a note to help recognizing them.
20,10,5 // [No effect]
1 // Number of quads for this checkpoint, 1 is enough.
-10.86 , 100 , -48.514 // Point #0 , see note 1.
-10.86 ,-100 , -48.514 // Point #1
-14.72 ,-100 , -48.510 // Point #2
-14.72 , 100 , -48.510 // Point #3
Note 1: These four points make the area through which your car must go, to get this checkpoint. The points: (look at the picture too)
Point #0 (A): Right , top , front
Point #1 (B): Right , bottom , front
Point #2 (C): Left , bottom , rear
Point #3 (D): Left , top , rear
If you put the "top" to 100 or something as big (which is clearly higher than the checkpoint is), you can get the checkpoint, even if you jumped over it.