在DTD文档中使用参数实体来替换所有的#PCDATA和CDATA。
<?xml version="1.0" encoding="UTF-8"?>
<spyBase>
<spy spyID="A001">
<firstName>Nikki</firstName>
<lastName>Devgood</lastName>
<AliasTab>
<alias aID="1">Spy Grrrl</alias>
<alias aID="2">La Femme Nikki</alias>
</AliasTab>
<MissionTab>
<mis mID="M101">
<date>2005/4/15</date>
<description>Crack the code</description>
<status>Mission Accomplished</status>
</mis>
<mis mID="M102">
<date>2006/2/15</date>
<description>Get the source</description>
<status>Mission Accomplished</status>
</mis>
<mis mID="M103">
<date>2006/5/4</date>
<description>Hit the target</description>
<status>In Progress</status>
</mis>
</MissionTab>
</spy>
<spy spyID="A006">
<firstName>Link</firstName>
<lastName>Lister</lastName>
<AliasTab>
<alias aID="3">LL</alias>
<alias aID="4">Fred</alias>
</AliasTab>
<MissionTab>
<mis mID="M104">
<date>2006/6/15</date>
<description>Shoot the rapid</description>
<status>In Progress</status>
</mis>
</MissionTab>
</spy>
<spy spyID="A003">
<firstName>Danger</firstName>
<lastName>Mause</lastName>
<AliasTab>
<alias aID="5">Big Ears</alias>
</AliasTab>
<MissionTab>
<mis mID="M105">
<date>2005/11/4</date>
<description>Get the <bigcheese></description>
<status>In Progress</status>
</mis>
<mis mID="M106">
<date>2006/4/4</date>
<description>Map the area</description>
<status>In Progress</status>
</mis>
</MissionTab>
</spy>
<spy spyID="A099">
<firstName>Barbara</firstName>
<lastName>Feldon</lastName>
<MissionTab>
<mis mID="M107">
<date>2006/5/2</date>
<description>Get Smart</description>
<status>In Progress</status>
</mis>
</MissionTab>
</spy>
<spy spyID="A004">
<firstName>Maxwell</firstName>
<lastName>Smart</lastName>
<AliasTab>
<alias aID="6">Inspector Gadget</alias>
<alias aID="7">Don Adams</alias>
</AliasTab>
<MissionTab>
<mis mID="M108">
<date>1967/2/15</date>
<description>Protect Chief</description>
<status>In Progress</status>
</mis>
<mis mID="M109">
<date>2006/6/15</date>
<description>Get some style</description>
<status>Mission Accomplished</status>
</mis>
</MissionTab>
</spy>
</spyBase>