When you have a "code list" that is subject to change over time, and you don't want to keep revving your schema versions, Genericode gives you a way to both define and validate the lists.
http://www.genericode.org/ At some point, this might even make a useful feature in libxml2. :-) .micah
thank You for your immediate response.I'm processing extern-data. In this data the attribute xml:lang is often used; before importing these data into our database,I check them with Your appreciated tool libxml via perl (linux). libxml incriminates the value "grc" of the attribute "xml:lang"