[TheArcher]

Take a look here

Btw e.g

pawn Код:

// under a callback or somewhere to call it
    if(IsPlayerInRangeOfPoint(playerid, 5.0, x,y,z)) // playerid - player which calls it, 5.0 - range point to activate in your case the mission, x,y,z floats saved as variable from you which gives the coordinates to execute the function.
    {
        //code
    }