One thing left out of the Continuity Bottle model that should be addressed is the concept of Tonal Pockets. What's that now?
Ok, you know how dynastic molecules swim through continuity like it's a liquid? Well, Continuity Fluid can have different consistencies throughout the bottle. Fluid consistency manifests itself as TONE. This explains the sometimes drastic retcon that occurs when, for example, Superman guest-stars in Plastic Man or Hitman. If the latter characters don't exist in a different world exactly, their stories are definitely told with a different point of view. When Superman swims into the tonally different fluid, he might become a lot sillier or a lot grittier.Now, Plastic Man isn't just swimming through a "funny" pocket. His essence so well matches the pocket's that he sticks with it (or it with him), bonding with his character concept, becoming, in a sense, one of his dynastic elements. ("What do you know about Plastic Man?" "He's funny.") It becomes very hard to dissociate Plastic Man from that tone even when he's in another style of story (say in the Mock-Realism of the Justice League). Other characters aren't so "essentially" tonal, which may explain why Batman has been used with a greater variety of tones (though there's a fluid consistency he definitely "prefers").
With this added element, the Vertigo Partition may just be a Tonal Pocket with a semi-permeable (editorial) membrane, though that's oversimplifying the various tones actually present across the line of books - horror, fantasy, gritty realism, high weirdness, etc. So a Pocket with a "mature readers" tone to be sure, a property the various fluid pockets inside the Partition all share. After all, Partitions still enclose continuity fluid, even if that fluid is different from the outside's. An Elseworld might only have one homogeneous tone (they often do), but it's still registering tonally. It still has consistency.
Tonal Pockets are an important concept because they help explain how the same Continuity can be so heterogeneous as to allow, for example, the grittiness of Alias, the superhero action of the Avengers, the irrevent edge of Nextwave and the indy vibe of Omega the Unknown. Is this really the same world, following the same rules? It is, because its constituent elements can meet each other, but we have to acknowledge that the Fluid in any given part of the bottle is not the same. Tonal Pockets can even stimulate Bubble Worlds to develop, especially in cases where the Bubble's rules are distinctive enough (Iron Fist being a good example here).
The above-pictured model obviously isn't complete because all stories have tones, so a detail would really look like this:
(Again, an over-simplification, but it does its job.) If there's still Fluid not color-coded, it's because a Continuity Bottle does have a "standard consistency". For these shared superhero universes, it's usually a mock-realism with a dash of grit (read: dismemberments). And since there's a standard, dominant Fluid, we can veritably talk about Pockets of substantially different consistency.
To be continued...