Vista - Consider marking it with the DataContractAttribute attribute

Hi,

I've got a WCF service and client. I'd like the service to expose a custom
structure used to return some data to the client of the form:

Public Structure TRANSACTION_RESPONSE
Dim ar As AUTHORIZATION_RESPONSE
Dim Fields() As String
End Structure

AUTHORIZATION_RESPONSE is an enum and Fields is an array of strings.

The service does not define this structure however, it is defined that
another library (IS.Services) which is included as a reference to the
service. I get this error when I create an interface and method on the
service which take string parameters and return a parameter of type
TRANSACTION_RESPONSE:

Type 'IS.Services+TRANSACTION_RESPONSE' cannot be serialized. Consider
marking it with the DataContractAttribute attribute, and marking all of its
members you want serialized with the DataMemberAttribute attribute."

The question is, how can I add the DataContractAttribute markers to a
library that is used as a reference within the service. It would be easy if
the service defined the structure itself - but it does not.