Envelope Structure

The whole message is contained inside an Envelope element.
The Envelope must contain exactly one Body element.
The Body element may contain as many child nodes as are required.
The contents of the Body element are the message.
If an Envelope contains a Header element (it can't have more) it must appear as the first child of the Envelope.
The contents of the Header and Body are application-dependent.
The encodingStyle in the envelope tells how the data is serialized