You may care to look at the HTML+ DTD. It includes support for both of
these, whilst remaining a simple generic format:
<P STYLE="MARGIN"> for sidenotes
<GROUP TYPE="CHAPTER"> ... </GROUP>
The GROUP element is intended to enclose books, chapters, sections etc.
which may even extend over multiple HTML+ documents. I have made a special
effort to help authors preserve information when converting to HTML+
while allowing simple browsers to ignore such information. This has been
done without the need to an explosion of tags as in the ISO work on SGML DTDs.
> lots of people are going to do lots of browsers. you have to pick
> which one you expect things to look "best" in and work to that. you
> may want to generate text for paper, in which case your original markup
> may get transmuted into a different format for the paper layout.
HTML+ is intended to allow people to generate high quality paper documents
and includes features such as sidenotes and floating panels to that effect.
Tob Raisch's style sheets for HTML also promise to give authors greater
control without compromising the presentation independence of HTML+ itself.
Cheers,
Dave Raggett