It retrieves the version attribute in string form.
它获取了字符串格式的版本属性。
2
If the information is suitable for attributeform, but could end up as multiple attributes of the same name on the same element, use child elements instead.
如果信息适合采用属性的形式，但可能造成同一元素中有多个同名的属性，则改用子元素。
3
Browsers, by default, will postback if the form doesn't contain an action attribute.