Hi,
I happen to work for GS1 🙂 I have no experience with BizTalk, but can help with our standards.
The package contains all the schemas needed to validate the sample instance. You can use the InvoiceProxy.xsd schema. It includes and imports all the component schemas, with the only exception of SBDH. You can simply add them to the proxy and then everything should be OK.
We organized the schemas in separate directories according to the namespaces used. They reflect our business process context (here ‘order’ and ‘pay’) and the context neatral components – ‘common’.
You can find more info in the User Guide: http://www.gs1.org/ecom/xml/implementation/guide and in our FAQ base: http://www.gs1.org/helpdesk – see eCom and XML section.
We do realise that this design is quite confusing and currently we are working an a simplified one, based on user feedback. The new and hopefully easier to understand schemas should be available next year as release 3.0.
You can access support in the country you are based in: http://www.gs1.org/contact/ I work for the Global Office, but we have Member Organisations in most of the countries and they provide technical support to user companies.
Wishing you success,
Ewa