Untyped messages inside an Orchestration allow for many different types of messages to be received by the same Orchestration using System.Xml.XmlDocument. This sample shows basic use of this feature.

Key Take Home Points:
- Common properties must be promoted in all of the different schemas (look at the promotions in both BookReview.xsd and MovieReview.xsd)
- Messages for type XmlDocument can be cast into different types
- Typed messages can be cast back into XmlDocument
- Blank Schema can be created and properties changed (look at Movie Review branch)
- This is using Property Promotion and Demotion in the XML Pipelines
- As a test, set the Send Pipeline to Pass Through and see the difference in the Movie Review output data.
- This will also work for distinguished fields

Get more information from the original blog post on this topic: http://www.biztalkgurus.com/biztalk_server/biztalk_blogs/b/biztalk/archive/2004/08/10/working-with-untyped-send-and-receive-ports-in-biztalk-orchestrations.aspx