The third category needs to extend an open XML through a simple way to describe structured data applications, XML is widely used to describe the user interface. XML describes the data itself. As the data show that separation of content, XML-defined data display allows you to specify different ways to make data more rationally demonstrated. Local data can be customer-configured, the user selection or other criteria to dynamically determine the manner shown. By XML, data can be granular updated. Whenever a part of the data after the changes, do not need to resend the entire structure of data.