The SIP isn't currently required to be consistent in the CAP sense of "consistent", but that is something people complain about. I think rightly, they point that the audit/compliance components of RegNMS are very troubling in the face of N inconsistent SIPs.

Similarly, people complain about the SIP feeds being latent and I'm sure it would be a very real problem if any single exchange being unavailable made the entirety of the SIP unavailable.

Its a fascinating problem because the engineering trade-offs are relatively static and well known, but each and every decision you could make provides an opportunity for arbitrage market activity that someone would consider predatory.

That we've layered a regulatory requirement that is pretty vague on some of the edge cases on top of this, just adds to it.

Please point to the exact paragraph in Reg NMS that backs up your story. To those reading, don't waste your time awaiting an answer because there is no such paragraph in Reg NMS.

The Regulations (Reg NMS) are very clear about this. That's why I was awarded $750K from the government after all.

I'm not sure what story you want me to back up is? If you are claiming that the current law requires the SIP to be consistent in the CAP sense, I'll defer to you and ask that you point out why you think so?

If you are asking about evidence that some people have claimed that the SIP being non-consistent is a problem for audit and regulatory compliance, is that not what you yourself are arguing in this post? http://www.nanex.net/Research/IsNBBOIgnored.html

I think maybe you are reading into my comment something that isn't there?