1  <?xml version="1.0" encoding="UTF-8"?>
 2  <grammar
 3      xmlns="http://relaxng.org/ns/structure/1.0"
 4      xmlns:a="http://relaxng.org/ns/compatibility/annotations/1.0"
 5      datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
 6  
 7  <define name="pattern1">
 8      <data type="string">
 9          <param name="pattern">-?([0-9]+(\.[0-9]*)?|\.[0-9]+)</param>
10      </data>
11  </define>
12  
13  <start>
14      <element name="elem1">
15          <attribute name="attr1">
16              <list>
17                  <ref name="pattern1"/>
18              </list>
19          </attribute>
20      </element>
21  </start>
22  
23  </grammar>