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I suggest your model does not yet identify what a "wiki" is.
I think that a "wiki" is a collection of articles and documents, a document itself being a collection of articles. (Incidentally I prefer "story" to "article" so as to distinguish from grammatical and other uses of "article" and it gives a clear path to tie into emerging argumentation models.)
A wiki "story" then is composed of one or more pages. I then look to XSL for the definition of a page, which divides rendition into repeatable header/footer areas & a body area. (In this regard, you can use "heading" or "caption" in the manner that you now seem to use for "header"). A "subpage" is another matter altogether, for its existence is functionally dependent on that of a superordinate page; a subpage often has overflow content from its superpage but it could be an earlier version of the superpage; in other words, a subpage contains material that is effectively attached to another page.
-- John McClure
Inline nowiki and monospace can be totally distinct in Creole (triple-braces for nowiki and double-sharps for monospace).
-- YvesPiguet, 2008-Sep-16