Line Type of an order line is changed even after the line is entered?

Hi, I wonder if 'Line Type' of an order line can be changed even after the order line is entered. For example, it was 'REGULAR' or 'STANDARD' order line when it was entered yesterday. And I change the same order line to 'RETURN' 2 days later. From the posting(http://www.oracleug.com/user-guide/order-management/order-header), I can see that Order Type for an order can be changed under 3 conditions mentioning there. But, I am not sure about 'Line type' of the order line. I would really appreciate if somebody can help me for this.

You can change the line type

You can change the line type if the order is in Entered Status. You cant change once the order is booked.

Check the below

Check the below screenshot.
This a system level process constraint. You cant update it.

Thank you very much for the

Thank you very much for the answer!

Thank you very much for the

Thank you very much for the clear answer and the screenshot