下面的例子通过外部实体引用，将文件order1.xml与文件order2.xml合并为一个文件directory.xml

清单1. 要合并的xml文档order1.xml：

<?xml version="1.0" encoding="GB2312"?>

<order>
  <item>
    <itemNumber>ksu-0384</itemNumber>
    <description>LCD液晶显示器</description>
    <quantity>1</quantity>
    <price>358.00</price>
  </item>
    <item>
    <itemNumber>ksu-0511</itemNumber>
    <description>音箱</description>
    <quantity>1</quantity>
    <price>16.50</price>
  </item>
    <item>
    <itemNumber>ksu-7710</itemNumber>
    <description>鼠标</description>
    <quantity>1</quantity>
    <price>8.50</price>
  </item>
</order>

清单2. 要合并的xml文档order2.xml：

<?xml version="1.0" encoding="GB2312"?>

<order>
  <item>
    <itemNumber>ksu-0652</itemNumber>
    <description>双飞燕键盘</description>
    <quantity>1</quantity>
    <price>35.00</price>
  </item>
    <item>
    <itemNumber>ksu-7720</itemNumber>
    <description>intel CPU</description>
    <quantity>1</quantity>
    <price>1650.00</price>
  </item>
    <item>
    <itemNumber>ksu-7010</itemNumber>
    <description>迈拓硬盘</description>
    <quantity>1</quantity>
    <price>850.00</price>
  </item>
</order>

清单3. 输出文档directory.xml，黑体字部分为实体声明及其引用：

<?xml version="1.0"?>
<!DOCTYPE directory [
   <!ENTITY disclaimer1 SYSTEM "./order1.xml">
   <!ENTITY disclaimer2 SYSTEM "./order2.xml">
]>
<directory>
   &disclaimer1;
   &disclaimer2;
</directory>

当符合 XML 1.0 的处理器读取文档时，就会扩展实体，用它的内容代替引用，因此完整的文档如下所示。

清单4. 带有扩展实体的文档显示（IE6中）：

  <?xml version="1.0" ?>
  <!DOCTYPE directory (View Source for full doctype...)>
- <directory>
- <order>
  - <item>
     <itemNumber>ksu-0384</itemNumber>
     <description>LCD液晶显示器</description>
     <quantity>1</quantity>
     <price>358.00</price>
    </item>
  - <item>
     <itemNumber>ksu-0511</itemNumber>
     <description>音箱</description>
     <quantity>1</quantity>
     <price>16.50</price>
    </item>
  - <item>
     <itemNumber>ksu-7710</itemNumber>
     <description>鼠标</description>
     <quantity>1</quantity>
     <price>8.50</price>
    </item>
   </order>
- <order>
   - <item>
     <itemNumber>ksu-0652</itemNumber>
     <description>双飞燕键盘</description>
     <quantity>1</quantity>
     <price>35.00</price>
    </item>
  - <item>
     <itemNumber>ksu-7720</itemNumber>
     <description>intel CPU</description>
     <quantity>1</quantity>
     <price>1650.00</price>
    </item>
  - <item>
     <itemNumber>ksu-7010</itemNumber>
     <description>迈拓硬盘</description>
     <quantity>1</quantity>
     <price>850.00</price>
    </item>
   </order>
  </directory>