this message inappropriate or redundant.
3. sender write LVB.
- sender down-convert MESSAGE from EX to CR
+ sender down-convert MESSAGE from EX to CW
sender try to get EX of ACK
[ wait until all receiver has *processed* the MESSAGE ]
sender down-convert ACK from EX to CR
sender release MESSAGE
sender release TOKEN
- receiver upconvert to EX of MESSAGE
+ receiver upconvert to PR of MESSAGE
receiver get CR of ACK
receiver release MESSAGE