Hi, how I can do to do options of coordinates for each circuit?

And if a player are in the coordinates, tell a message if he are in?

You need to request the IS_MCI packets and for each IS_MCI packet you receive there will be up to 8 compcar "sub packets" (or structs) where the node, lap, plid, position, and x, y and z coordinates are embedded. You read them from here.

To discover if a player is within a set of coordinates you simply compare the coordinates you get with a set of known values.

I do not understand since one becomes

If u can, you could do an example, please (I am noob)