在DTD文檔中使用參數實體來替換所有的#PCDATA和CDATA。

w3.xml：

<?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 &lt;bigcheese&gt;</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>

w3d.dtd：

利用參數實體把“#PCDATA”設置參數爲pc

<!ENTITY % pc “#PCDATA”>

最後，代碼如下：

<?xml version="1.0" encoding="UTF-8"?>
<!ENTITY % pc "#PCDATA">
<!ENTITY % cd "CDATA">
<!ELEMENT spyBase (spy+)>
<!ELEMENT spy (firstName, lastName, AliasTab?, MissionTab)>
<!ELEMENT MissionTab ((mis+))>
<!ELEMENT AliasTab ((alias+))>
<!ELEMENT mis ((date, description, status))>
<!ELEMENT lastName (%pc;)>
<!ELEMENT firstName (%pc;)>
<!ELEMENT description (%pc;)>
<!ELEMENT date (%pc;)>
<!ELEMENT alias (%pc;)>
<!ELEMENT status (%pc;)>
<!ATTLIST spy spyID ID #REQUIRED>
<!ATTLIST mis mID ID #REQUIRED>
<!ATTLIST alias aID CDATA #REQUIRED>

運行無報錯