1<?xml version="1.0"?>
2<!DOCTYPE main [
3 <!ELEMENT main (a*)>
4 <!ATTLIST main list CDATA #REQUIRED>
5 <!ELEMENT a (#PCDATA)>
6 <!ATTLIST a id ID #REQUIRED>
7]>
8<main list="y w z">
9 <a id="w">W</a>
10 <a id="x">X</a>
11 <a id="y">Y</a>
12 <a id="z">Z</a>
13</main>