If you are defining an application in an xml file , you must replace reserved xml characters , such as 如果您在xml文件中定义应用程序，则必须使用实体引用替换保留的xml字符如“
Because the ampersand is a reserved character in xml , the query string includes the entity reference 由于“ and ”符( & )在xml中是一个保留字符，因而查询字符串包含的将是实体引用
And , as with entity references , changing the value of the parameter entity changes the definition for all elements 和实体引用一样，更改参数实体的值会更改对所有元素的定义。
The reader normalizes each individual text node independently from the content of adjacent entity reference nodes 读取器独立于相邻实体引用节点的内容之外对每个单独的文本节点进行正常化。
When a sax parsing process runs across this entity reference , it has to resolve the entity into another piece of content 当sax解析过程运行到该实体引用时，它必须将该实体解析成另一段内容。
In other words , parameter entities are generally not used in dtds as entity references are generally used in xml documents 换句话说，在dtd中使用参数实体通常并不象在xml文档中使用实体引用那样。
The entity can be referred to by an entity reference to insert the entity s contents into the tree at that point 实体可以通过实体引用进行引用，将实体的内容插入树中的相应位置。实体声明出现在dtd中。
The entity reference is untouched , but now when it s expanded , it uses the contents of the file , so the document becomes 实体引用并未改动，但是当对其进行扩展时，使用的是文件的内容，因此文档将变成：
Also like entity references , you can define a parameter entity inline within an xml document , or leave it in a separate dtd 也和实体引用一样，您可以直接在xml文档内定义参数实体，或将其放在单独的dtd中。
