PiusV, I came across this discussion about the nature of the Ordinary Magisterium. It seems relatively informative, but I do think it conflates "teaching" with "discipline", and therefore it loses some credibility in my view. The examples of eating meat on Fridays of Lent is a matter of discipline, not teaching. I have no doubt that synods may define discipline, which we are required to obey (assuming it is not intrinsically immoral). But I'm not convinced that they can define doctrine (teaching), which we are required to believe.
I'm interested in what you think.