The requirement for datadeclaration vary among different programming languages but can include such values such variable name , data type , initial value , and size specifications, etc.
但是要包含这样的数值，比如：可变量的名称、数据方式、初始值以及尺寸规范等。
2
The reason that this is required is that an XML document might require information other than the business data and names — such as an XML declaration.
需要这个的理由是XML文档可能需要除业务数据及名字之外的信息——如XML声明。
3
Note the XML declaration at the start of the data.