What entities do you use for common XML dialects?

[bryan rasmussen <rasmussen.bryan@gmail.com>]

Hi,

I would like to get links to or examples of entities that people
return to again and again for common XML dialects.

In this case I am not talking about the obvious ones for XHTML etc.
but the more esoteric uses such as entities with markup for expansion
in processing chains.

Do you find that there are entities that you use a lot for particular
dialects to assemble XML for processing?

Normally the entities I see are for Docbook, XHTML, MathML...
I am wondering about if people have entities they use a lot for XSLT,
XSL-FO, SVG, XSD, XBRL...that vary significantly from the XHTML
entities..

As an aside on this - I want to find XML Catalogs maintained by
various organizations, if you do not know the location of the XML
Catalog or the purpose of it but just want to find every incident of
an XML Catalog how would you do it (aside from the obvious write a
webcrawler), does anyone have a search engine trick, know a central
resource that tries to maintain lists of all catalogs (for example
some part of XML Coverpages or a way to search there that tells me
every XML Catalog they have listed)

Best Regards,
Bryan Rasmussen