TCP and SCTP sequence analysis code

So if I were to ever actually find the time to study the TCP sequence 
analysis code (which detects retransmissions, associates acks with the 
acked data, etc.) in the hopes of doing something similar in SCTP, is 
there anything I should know about the TCP code?  Any known deficiencies 
or things that could be done better?

(Of course I'm probably kidding myself that I'll ever find the time, but 
I keep getting confused by retransmissions that I didn't notice were 
retransmissions the first N times I looked at them.)