This paper addresses the interplay between complex business requirements and technical design to maximize interoperability by leveraging the XSD type-derivation hierarchy. It provides a brief background of the OASIS UBL TC, the work of the Context Methodology subcommittee, and the concept of processable business context description as inherited from the ebXML Core Components work. The focus is on the difficulties of modelling complex business relationships within the limitations imposed by XSD type derivation mechanisms. For example, how can the perceived need to delete required components be made to work with XSD's type derivation constraints? While very much aligned with the spirit of the XSD specification, the methodology described results in a powerful and non-obvious design philosophy that impacts both document design and management.

UBL places emphasis on interoperability within business-to-business e-commerce, both within and across verticals. The range of business requirements is vast, and a number(B of standards organizations has evolved to try to provide interoperable specifications. The UBL approach to extension and derivation of XML business documents leverages this existing hierarchy, and utilizes the type-derivation and polymorphic features of XSD to allow a greater degree of inheritance and interoperability than has historically been possible. Ultimately, XSD is used to model the relationships existing among the players in the business world, defining and limiting how type derivation may occur within a UBL-compliant universe.

This approach resolves the tensions between the XSD mechanisms and complex real-world business requirements. The paper provides a unique view of how UBL will function in the realm of standardization, as well as exemplifying a design philosophy that has implications for application design and the general use of XSD to promote data interoperability.