BTS operates with messages constituted with one or more parts. Since XSD schema defines a single part with a message, it may be used only to promote the fields from such a part, not from message at whole. The filelds promoted this way called distinguished. If the message defined as .NET class, [DistinguishedField] attribute should be applied to the corresponding member.
As opposite, property fields applied to the whole message and invented to describe the 'context' of the message with all parts inside. For this purpose, property fields are stored outside the parts schemas in the special type of schema designed exclusively for this matter.
For both field types there is the same 'promotion' mecanism.
The property schema by itself is defined by using annotation like this:
<xs:annotation>
<xs:appinfo>
<b:schemaInfo schema_type="property" xmlns:b="http://schemas.microsoft.com/BizTalk/2003" />
</xs:appinfo>
</xs:annotation>
Once defined, such a schema may only contain one level elements each of them is usual XSD element declaration. In the part XSD, the property schema is imported using directive of annotaion extension and the root element of the part schema is extended by