XML 实体 - 我的代码有什么问题？

Question

我正在 XML 参加 class，我必须阅读这本名为 "INeasysteps" 的书。我正在尝试遵循有关 "Adding Comments and Entities" 的教程之一，但是当我将其放入浏览器时，我不断收到响应：

Blockquote XML Parsing Error: undefined entity Line Number 11, Column 13: Blockquote

这是我的代码：请让我知道我做错了什么。仅供参考，Jedit 解析器中没有错误，但是当我将 xml 代码放入浏览器时出现上述错误：

<?xml version="1.0" encoding="UTF-8" ?>

<!-- XML in easy steps - Page 40. -->

<?xml-stylesheet 
type = "text/css" href = "history.css" ?>

<!DOCTYPE doc SYSTEM "history.dtd" >

<doc>
<para>Both &html; and &xml; are derived from &sgml; which is, in turn, a descendant of the &gml; that was developed in the 1960s by IBM. </para>
</doc>

这是 history.dtd 文件

<!-- Define the root element. -->
<!-- May contain one child element called para. -->
<!ELEMENT doc (para)>

<!-- Define the child element. -->
<!-- May contain Parsed Character Data. -->

<!ELEMENT para (#PCDATA)>


<!-- Define entity values. -->
<!-- Common markup language acronyms. -->
<!ENTITY html
"HyperText Markup Language (HTML)" >
<!ENTITY xml
"eXtensible Markup Language (XML)" >
<!ENTITY sgml
"Standard Generalized Markup Language (SGML)" >
<!ENTITY gml
"Generalized Markup Language (GML)" >

Answer 1

大多数浏览器不会加载外部实体。如果要在浏览器中打开 XML 文件并正确解析实体，请将实体声明添加到内部子集（文档类型声明中的 [ 和 ] 之间）：

<?xml version="1.0" encoding="UTF-8" ?>
<!-- XML in easy steps - Page 40. -->
<?xml-stylesheet type="text/css" href = "history.css" ?>
<!DOCTYPE doc SYSTEM "history.dtd" [
<!ENTITY html "HyperText Markup Language (HTML)" >
<!ENTITY xml "eXtensible Markup Language (XML)" >
<!ENTITY sgml "Standard Generalized Markup Language (SGML)" >
<!ENTITY gml "Generalized Markup Language (GML)" >
]>
<doc>
    <para>Both &html; and &xml; are derived from &sgml; which is, in turn, a 
        descendant of the &gml; that was developed in the 1960s by IBM. </para>
</doc>

XML 实体 - 我的代码有什么问题？

XML Entity- what's wrong with my code?

xml

dtd

entity