How professional ELO determined?

I read the Chinese Weiqi Association if for strong amateurs and pros. So how is the starting ELO determined for these big wig associations?

There are qualifying tournaments organized by province. I dunno the detail for each province but i participated in the Sichuan ones (Chengdu). It’s hold regularly every 3 months and you play a bunch of games, 8 I think on 4 days, with players of same level, 99% are children. Entrance group level is just before dan.
For pro it’s in Beijing and… i don’t know more.