The TCP FSM is of course the most critical component of the transport.  

It would be good to list all that is not included in the Yang model that exists in the TCP MIB.  Also would be helpful as to reasons why.

I see mentioned that RTO is not part of the Yang model, however to be complete I think it should be included.

The yang model seems to not have  all the TCP FSM states listed below:
Closed
Listen
SYN RCVD
SYN Sent 
Established 
FIN wait 1
FIN wait 2
Closing 
Time wait 
Close wait 
Last Ack


Also the Yang model does not reference the TCP Flag bits set during state changes in the FSM below as well as flag combinations for example for establishment state you sent SYN, receive SYN/ACK, ACK

URG
ACK
PUSH
RESET 
SYN
FIN

I also don’t see anything in the Yang model on TCP window and window scaling and CWIN congestion control algorithm backoff.  

Also I don’t see any mention in the Yang model about the well known port range 0-1023 and > 1023 anonymous port range for the TCP socket to be established.

Also mention about the TCP TCB control block.

Local IP Local Port 
Remote IP Remote Port 
Interface 
Process 
State 
Local/Send window 
Remote/Receive window
Send SQ Ack
Send SQ Un-ack
Send SQ Next 
Not to be sent
Receive Next 
RTT
Buffer pointer