DOCBOOK-APPS: Foilgroup nesting (slides.dtd)

Hello,

I was surprised to see that nesting of foilgroups is not allowed in the
slides.dtd (at least not in the version I have installed from
SourceForge, 3.0b!, or in the SourceForge CVS).

I searched a bit on Google and in the message list archives, but could
not find a discussion about this subject. Is there a reason why this is
not allowed, or is it just something nobody thought about? I can imagine
situations where nesting of foilgroups would be needed, so I suggest it
would be allowed in the DTD.

Greetings,

Jan Fabry

PS: Thanks, again, for everybody who created DocBook. It's really a
great way to learn about XSL and content-centered formatting.