It seems to be a naming convention for provisional names (https://www.quora.com/How-are-asteroids-named)
2019 OK :
- "2019" => discovered in 2019
- O => discovered in 2nd half of july
- K => 10th object discovered in this period
2019 OK :
- "2019" => discovered in 2019
- O => discovered in 2nd half of july
- K => 10th object discovered in this period