5. Other DTDs
A brief digression into other DTDs may help make clear what parts of
the previous section were specific to DocBook and what parts are general to
all structural-markup languages.
TEI (Text Encoding
Initiative) is a large, elaborate DTD used primarily in academia for
computer transcription of literary texts. TEI's Unix-based toolchains
use many of the same tools that are involved with DocBook, but with
different stylesheets and (of course) a different DTD.
XHTML, the latest version of HTML, is also an XML application
described by a DTD, which explains the family resemblance between
XHTML and DocBook tags. The XHTML toolchain consists of web browsers
and a number of ad-hoc HTML-to-print utilities.
Many other XML DTDs are maintained to help people exchange
structured information in fields as diverse as bioinformatics and
banking. You can look at a list of
repositories to get some idea of the variety out
there.
Free eBook: 
