Simplified DocBook Processor

 SDoP (Simple DocBook Processor) reads a Simplified DocBook XML file, processes
 it into typeset pages, and outputs the result as PostScript (which can easily
 be converted to a PDF). It is "simple" because it supports only a subset of
 DocBook, and also because it does not make use of a DTD or stylesheets or any
 other heavyweight apparatus. It is a single program. SDoP is used to format
 the Exim reference manual.