Extending DTD + FOP Books

Hi. I'm currently building a set of stylesheets for my new website. I
have adopted the approach of writing pages in XHTML Basic (ie no tables
etc) and then rendering simple and complex versions of these pages via
XSLT.

This is all working fine. However, I have started to add small
embellishments to the XHTML to represent aspects of my writing. For
instance, I have added a "quotable" element which is always in a
paragraph tag. This element is intended to represent spans of text that
are quotable eg they may be represented in the complex version as
pullquotes. Now, how would I go about extending the XHTML Basic DTD so
that i can validate my XML against the XHTML DTD and my own?

Also, does anyone have any FOP book recommendations?

-- 
Mike.Moran@xxxxxxxxxxx 
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