XML DocBook I.

XML by default uses UTF-8 or UTF-16 encodings

UTF-8/16 are able to store national characters, but not every editing tool supports them

users like to write content in single-byte encodings like ISO-8859-2, windows-1250, …

in XML you can set used encoding in XML declaration

<?xml version="1.0" encoding="iso-8859-2"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" 
                      "http://www.oasis-open.org/docbook/xml/4.0/docbookx.dtd">
...