Draft coding chapter for forthcoming book

I am working on a book about Internet application layer
protocols and standards. The book is based on a course,
which I give at my university.

I have now revised the chapter about coding from this book,
by adding a short description of HTML, CSS and XML. The new
version of the coding chapter can be found at
http://dsv.su.se/jpalme/abook/coding.pdf

I would appreciate if some of you experts on this area
could check the text for accuracy.
-- 
Jacob Palme <jpalme@dsv.su.se> (Stockholm University and KTH)
for more info see URL: http://www.dsv.su.se/jpalme/