Sources
nBook
Professional XML by Birbeck et al.,
Wrox Press nPractice
C++/Smalltalk application with SAX nTutorial
XMLSpy Suite
XSLT Designer nDocumentation
Scalable Vector Graphics Specification
Where I found the information I have on this topic.
I started my present investigation into XML with a book, a very thick book, which in retrospect I can’t recommend.  It is a place to start and this one does a reasonable job explaining what all of the abbreviations mean and how they relate.  I have read worse books on XML, but luckily I can’t remember much about them.
Does anyone here have a book that they can actually recommend?
I read the book because I was about to write an application by chance in C++ and Smalltalk that processes XML data.  The C++ part does it without any library support and can stand alone.  The Smalltalk portion uses a wrapper around a SAX (Simple API for XML) implementation.
In doing this I became aware of some products that are used in XML development.  One was simply an updated version of my programmers editor and another is XMLSpy, which comes with a couple of tutorials that are lasted here.
Also, I read a couple of pages from the SVG Spec.