为什么WCF有时会在生成的代理类型的末尾添加“Field”？

Basically, I have a server-side type "Foo" with members X and Y. Whenever I use Visual Studio's "Add Server Reference" then I see the WSDL and the generated proxy both append the word "Field" to all the members and change the casing of the first letter. IE, "X" and "Y" are renamed "xField" and "yField". Any idea why this is happening? I can't figure out the pattern.Basically, I have a server-side type "Foo" with