John,
The structure of the XML can be validated within TN at the document level or at the Processing Rule level. However if you want to validate the data, you may do so by defining an XSD and using the pub.schema:validate as the first step in your IS service that processes the XML. If XSD is not an option, then you can use a custom validation service as the first step in your processing service. The custom validation service may be built within IS or may reside in an external jar.
My two cents.
R
#webMethods#Integration-Server-and-ESB#B2B-Integration