A property schema is used with one of the two mechanisms that exist within BizTalk Server for what is known as property promotion. Property promotion is the process of copying specific values from deep within an instance message to the message context. From the message context, these values are more easily accessed by various BizTalk Server components. These components use the values to perform actions such as message routing. Promoted property values can also be copied in the other direction, from the more easily accessible message context back into the depths of the instance message, just before the instance message is sent to its destination. A property schema is a simple version of a BizTalk schema that plays a role in the process of copying promoted properties back and forth between the instance message and the message context.