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>
24