function addSnap(top, left, numberVal) {

    //Check if the data already contains a value for the pair.
    if (contains(sendingData, "[block-" + top + ":" + left + "]", "[/block]")) {
        //The sendingData already contains the current block.
        var getData = splitReduced(sendingData, "[block-" + top + ":" + left + "]", "[/block]");
        var getData_whole = "[block-" + top + ":" + left + "]" + getData + "[/block]";

        sendingData = sendingData.replace(getData_whole, "")
    }

    //Validate the positions
    var positionValidated = false;
    for (var i = 0; i < validPositions.length; i++) {
        if (validPositions[i][0] == top && validPositions[i][1] == left) positionValidated = true;
    }

    if (!positionValidated) {
        //The position is not valid, send a nasty error-message.
        return;
    }

    //Create a new block with the data.
    var blockData = '[block-' + top + ':' + left + ']' + numberVal + '[/block]';
    sendingData = sendingData + blockData;

    //DEBUG:
    console.log("Added " + top + ":" + left + " to data. Ready to ship.");
}