DRAG DROP
There is WCF (Windows Communication Foundation) service PassGuideService.
A data contract PassGuideContract for PassGuideService is being implemented.
PassGuideContract must be forward-compatible.
The round trips must include the information in PassGuideContract.
It should be able to add ew data members to PassGuideContract.
You do have to follow a strict schema validitiy.
Which interface should be used for PassGuideContract class?
Answer: 
Explanation: