A Prime schema

<?xml version="1.0"?>
<element name="numbers" xmlns="http://relaxng.org/ns/structure/1.0">
  <oneOrMore>
    <element name="number">
      <data type="prime"
            datatypeLibrary="http://ns.cafeconleche.org/relaxng/primes"/>
    </element>
  </oneOrMore>
</element>

datatypes d = "http://ns.cafeconleche.org/relaxng/primes"

element numbers {
  element number { d:prime }+
}