There are conventions for identifying these artifacts in an html document, but there is
<br />nothing incorporated into HTML that declares unambiguously that (for instance) an
<br />H2 with a class of &quot;chapter-head&quot; is the way a given document does it. Nor is there
<br />an implicit way to declare such a structure as metadata.
<br />
<br />All we do is choose one of the ways we saw someone else do it, or make up another
<br />way ourselves. But it doesn&#39;t inhere to HTML, nor is it particularly easier than any
<br />other form of representation. It&#39;s equivalent to saying &quot;It&#39;s a new chapter when there
<br />are four blank lines, and the first paragraph is the chapter title&quot; in a text document.
<br />
<br />And including images by reference with a url is an explicit admission that it stands 
<br />outside the HTML structure. There&#39;s no assurance that the reference is even available
<br />or legitimate if that document were copied elsewhere.
<br />
<br />And there&#39;s no way within the bounds of (X)HTML standards to provide such a capability. 
<br />
<br />Certainly we can&#39;t publish or even describe an API that would provide unambiguous 
<br />text and metadata sufficient to construct a properly structured ebook in any other 
<br />representation than the one in which it is stored. And among the storage formats 
<br />we provide from which such information might be inferred, it seems to be in most 
<br />cases the plain-text format that is most accessible. At least whatever conventions
<br />there are seem to be more consistently adhered to.
<br />
<br />&gt;