http://www.cafeconleche.org/namespaces/people is the namespace URL for an XML application describing people in a data-oriented fashion used as an example in XML in a Nutshell, second edition by Elliotte Rusty Harold and W. Scott Means (O'Reilly & Associates, 2002).
Several examples in this book address this application in one way or another. These include:
This document itself is Example 14-2 from the RDDL chapter.