When overridden in a derived class, gets a set of processing-level annotations to the message.
Assembly: System.ServiceModel (in System.ServiceModel.dll)
Because information in headers is transmitted on the wire, an entity that examines a header must support the underlying version(s) of the protocols used by the header. However, properties provide a more version-independent way of annotating a message.
Available since 4.5
Available since 3.0
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0