DataSetMessages and header to facilitate delivery, routing, security and filtering

Note 1 to entry: The Publisher hands off the NetworkMessage to the Message Oriented Middleware (transport layer) to deliver DataSetMessages to the Subscribers.

Note 2 to entry: The term message is used with various connotations in the messaging world. The Publisher might like to think of the message as an immutable payload handed off to the Message Oriented Middleware for delivery. The Subscriber often thinks of the message as not only that immutable payload from the sender, but also various annotations supplied by the Message Oriented Middleware along the way. To avoid confusion the term DataSetMessage is used to mean the message as supplied by the Publisher for a DataSet and the term NetworkMessage is used to mean the DataSetMessage plus sections for annotation at the head and tail of the DataSetMessage.