WCF service interface

Question

Is it possible to declare method in service interface without operationcontract attribute?

Example is mention below. 

 

[ServiceContract]

interface IService

{

[OperationContract]

void Display();

 

//Without Operation contract 

void Show();

}

class Service : IService

{

public void Display()

{

   throw new NotImplementedException();

}

public void Show()

{

throw new NotImplementedException();

}

}

 

1. If yes then what is use of it. 

 

Interviewer asked me this question recently. Please help me.