[tcpm] Is ECN a valid TCP header flag?

[t petch <[e-mail]>]

This question came to me seeing the IESG discussion of an OPSAWG I-D 
which modelled, in part, TCP, in YANG, but did not model it the way TCPM 
does.

There is a lot of this about, as in I2NSF, which has the most detailed 
model I see of TCP although not in a way that is likely to be used by 
those operating TCP.

Thus draft-ietf-i2nsf-nsf-facing-interface-dm provides identities such as
     identity tcp-flags {
which is then used as

   base tcp-flags;
     identity cwr {
     identity ecn {
     identity urg {
     identity ack {
     identity psh {
     identity rst {
     identity syn {
     identity fin {
with descriptions and references.  My knowledge of this is limited but I 
suspect that the reference for 'ecn' should be RFC3168 and not RFC793 
but then should it be 'ece' and not 'ecn'?  I suspect that a TCP expert 
might see rather more idiosyncrasies.  Is RFC793 still the right 
reference or should it be 793bis? Both are used.

Details of TCP also appear in
draft-ietf-i2nsf-capability-data-model
draft-ietf-i2nsf-consumer-facing-interface-dm
draft-ietf-i2nsf-nsf-monitoring-data-model
as do details of IP and a wide range of application and transport 
protocols; I suspect that those with an attention to detail and an 
interest in transport could have a field day here.

Tom Petch