There are literally hundreds of commercial or not for profit organizations which develop XML schemas for business information exchange between business partners or enterprise systems. 

OAGIS - The Open Applications Group is a non-profit consortium focusing on best practices and processes based on XML content for eBusiness and Application Integration. It has over 6 years of extensive experience in building industry consensus for business software application interoperability and have developed a repeatable process for quickly developing high quality business content and XML representations of that content.

RosettaNet - Non-profit organization, RosettaNet is a consortium of major Information Technology, Electronic Components and Semiconductor Manufacturing companies working to create and implement industry-wide, open e-business process standards. These standards form a common e-business language, aligning processes between supply chain partners on a global basis.

xCBL - xCBL is a set of XML business documents and their components, distributed freely. In addition to using the business documents, you can also use the component library to build your own documents. Either way, using xCBL promotes interoperability between applications.

UBL - This is a work in progress, connected to the ebXML Core Components. "The purpose of the UBL [working group] is to develop a standard library of XML business documents (purchase orders, invoices, etc.) by modifying an already existing library of XML schemas to incorporate the best features of other existing XML business libraries. UBL is intended to become an international standard for electronic commerce freely available to everyone without licensing or other fees".

---

High hopes for the Universal Business Language by Edd Dumbill and Jon Bozak