Re: Nothing installing after baseOS
I can certainly see the point of having a guaranteed sort order, but this seems more like a 'best practice' than a programmatic limitation. I can more see your point about avoiding extraneous files (the examples you mentioned could be easily overcome by, say, testing to see if the given items are folders, but I can see the case in which an errant folder could end up there as well.
The XX-String model is certainly a good option. I wonder if adding a file extension to the folder name, or something might be intuitive? I'd say, in fact, just making bundle file, which could offer other advantages as well, but this might be a bit of impediment for the new user, I suppose. But, I wonder if maybe just having the folder named, say "01-Fake Update.instadmg" would do a good job of offering maximum flexibility in naming, while simultaneously making it clear what the folder is, semantically?
It also, I think, might be a good planning mechanism for a future state, where we want to develop a proprietary format? Imagine, for instnac,e a future condition in which apple releases two versions of it's updates, a .pkg file, and a .instadmg file that's pre-edited to work optimally with the instadmg process (I'm thinking, here, of all the packages I've hade to edit ever-so-slightly to make them work with instadmg). As instadmg is developing into a bonafide standard, I'm just thinking we may as well leave ourselves room to develop future standards?
Just my two scents, quite possibly I'm dead wrong