OnOrderUpdate - Event subscribed

Hi

I have subscribed to Event "OnOrderUpdate(Order OrderData)".

I see only 3 different status in the code

KiteConnect.Constants

// Order status
public const string ORDER_STATUS_COMPLETE = "COMPLETE";
public const string ORDER_STATUS_CANCELLED = "CANCELLED";
public const string ORDER_STATUS_REJECTED = "REJECTED";

Question:

1) Any reason why "Update" status is not there?
2) If I have placed an Order for 100 quantity and only 50 is filled, what will the Status of OrderData.Status when "OnOrderUpdate" is called?