> Actually, this capability is already in HTML+ in the form of the <RENDER>
> tag. <RENDER> allows you to specify an arbitrary tag name (such as SLANG) and
> define the combination of styles to be applied to phrases marked with that
> tag (such as B, I, Q, TT, and so on, and P which indicates the tag should
> cause a paragraph break).
<RENDER> and user-defined elements are still controversial,
since users have to modify the DTD for it to work. The
mechanism for doing so is not at all intuitive without a
thorough understanding of SGML, and it's a lot more work for
browsers. (Well, not really; browsers could continue to ignore
the DTD internal subset and only pay attention to <RENDER> tags,
but that will only encourage the proliferation of illegal HTML
on the Web.)
InfoMaster/IBMIDDoc lets users define new semantic classes
without modifying the base tag set. This seemed like
a cleaner approach to me.
--Joe English