Limitations of XML Document Type Usage
Although XML document types and IS document types can be used in nearly identical ways, there are some limitations in the usage of XML document type:
XML document types cannot be made publishable. That is, an XML document type cannot become a publishable document type.
XML document type cannot be used in web services, which includes the signatures of services used as operations, headers, faults, and the
pub.soap.handler* services.
XML document types cannot be used as the top-level element in a service signature. That is, on the Input/Output tab, you cannot specify an XML document type for the
Input field or
Output field.
XML document types should not be created from an XML schema definition in an Event Type Store.
XML document types should not be created from e-forms.