Schematron is a rule based validation language for structured documents. It was designed by Rick Jelliffe in the late 1990s [JELLIFFE1999] and standardized as part of the ISO Document Schema Language Definitions (DSDL) family in 2006. The last non-ISO version was Schematron 1.6, published in 2002. [JELLIFFE2002] Since the standardization as ISO/IEC 19757-3 two editions have been published. The 2nd edition in 2016, the 3rd edition in 2020. The 3rd edition of ISO Schematron will most likely be the last: The working group was disbanded and, more importantly, ISO removed Schematron from the list of publicly available standards, effectively putting an end to ISO Schematron as an Open Standard.

While losing an Open Standard is annoying it gives the opportunity to look at the specification as an object of an analytic inquiry. Rather than comparing Schematron with other schema languages we could look at ISO Schematron’s concepts and ask what function they serve or which topic they cover. This analytic perspective may help structuring a discussion of potential shortcomings or missed opportunities.