What does RLC Receiver entity should do if it receives VT_A greater than VT_S?

Question

While going through 3GPP 36.322 specification. I saw a routing box inside the figure. Can anyone please explain the uses of it ?

Answer 1

I don't think if it is possible, VT(A) is the lower edge of acked window where as VT(S) hold the SN of new AMD PDU to be generated. So until VT(S) is not sent how can VT(A) will be incremented