为什么需要为int和Data设置Web Service DataMember的Specified Attribute，而不是为String设置

I have created a web service via WCF. Then I exposed it as a web service to make it usable with a .NET 2.0 application. I created some DataContract with DataMember that could be used for by the exposed OperationContract.I have created a web service via WCF. Then I ex