Wait are there stricter conditions for DIYs than for organised events then? I've never considered doing a DIY but that surprises me.
In my view an audax is just riding your bike a long way for the sake of riding your bike a long way. Don't mind whether there are controls with cake and mechanics on hand, whether you're riding on the wheel of a dozen Swedes, whatever. The difference between an audax and a race is not how spread out the participants are but that the aim of a race is to win. The 24hr TT is an interesting anomaly! The fact that it was a validated long distance ride before there was a UK-based long distance ride validator I suppose means it has a place in the history of UK audaxing.
As far as self-sufficiency goes - which, sure, is a key part of the audax idea, I guess I think of it in terms of self-sufficiency on the bike, i.e. carrying with you what you need to keep moving forwards. The rules for the self-sufficiency ultra race things obviously need to be much stricter than what I think is needed for a ride to be an 'audax'.
I mean people take all kinds of different standpoints on stuff like this and I'm not hugely invested in it either way. I just hadn't heard about DIYs being more strict.
In other news, I'm planning on ECEing the Mildenhall Festival 200 next saturday (from Colchester) to try and build up some condition for the Fenland Friends - having not done >=100 miles yet this year :s