[CalvinC]

Just put together an example.
Think it like x[], y[] and z[] are your different coordinates, i just numbered them to make it easier to understand how they all relate.

pawn Код:

SetPlayerRaceCheckpoint(playerid, 0, x[0], y[0], z[0], x[1], y[1], z[1], 5);
    // Sets the players race checkpoint to the coordinates number "0", and the arrow will be pointing to the next checkpoint, at coordinates number "1"

public OnPlayerEnterRaceCheckpoint(playerid)
{
    if(IsPlayerInRangeOfPoint(playerid, 5, x[0], y[0], z[0]))
        // If the player is in range of the coordinates number "0", the same coordinates as the first checkpoint is at
    {
        SetPlayerRaceCheckpoint(playerid, 0, x[1], y[1], z[1], x[2], y[2], z[2], 5);
            // Then set the next checkpoint, at coordinates "1", and make the arrow point to coordinates number "2"
    }
    if(IsPlayerInRangeOfPoint(playerid, 5, x[1], y[1], z[1]))
        // If the player is in range of the coordinates number "1", the same coordinates as the second checkpoint is at
    {
        SetPlayerRaceCheckpoint(playerid, 0, x[2], y[2], z[2], x[3], y[3], z[3], 5);
            // Then set the next checkpoint, at coordinates "2", and make the arrow point to coordinates number "3"
    }
    // Continue for all checkpoints
    return 1;
}