xml 文档树
All elements can have sub elements (child elements):
文档中所有的元素都可以包含二级元素（即：子元素）：
<root> <child> <subchild>.....</subchild> </child> </root> |
The terms parent, child, and sibling are used to describe the relationships between elements. Parent elements have children. Children on the same level are called siblings (brothers or sisters).
这里提到的一些术语，如：父元素、子元素、同级元素使用与描述元素之间的相互关系的。父元素包含子元素；和子元素同级的称为同级元素（或兄弟、姐妹元素）。
All elements can have text content and attributes (just like in HTML).
所有的元素都包含文本内容和属性（这点和HTML极其类似）。
Example:
案例：
The image above represents one book in the XML below:
上述图表代表了下述XML文档中的一本书：
| <bookstore> <book category="COOKING"> <title lang="en">Everyday Italian</title> <author>Giada De Laurentiis</author> <year>2005</year> <price>30.00</price> </book> <book category="CHILDREN"> <title lang="en">Harry Potter</title> <author>J K. Rowling</author> <year>2005</year> <price>29.99</price> </book> <book category="WEB"> <title lang="en">Learning XML</title> <author>Erik T. Ray</author> <year>2003</year> <price>39.95</price> </book> </bookstore> |
The root element in the example is <bookstore>. All <book> elements in the document are contained within <bookstore>.
案例中的根元素是<bookstore>。文档内所有的<book>元素都位于<bookstore>内。
The <book> element has 4 children: <title>,< author>, <year>, <price>.
与此同时，<book>元素还包含了4个子元素：<title>、< author>、<year>、<price>。
