In the previous sections I discussed some shortcomings of the current ISO Schematron specification. Some could be fixed by simply amending the ISO specification, some like the lacking inclusion mechanism require more substantial work. Ideally, these issues would be addressed by a future 4th edition of the ISO Schematron specification. But alas, this seems unlikely.

Maybe ISO Schematron becoming proprietary gives us the opportunity to start anew; or rather start with the core ideas of the Schematron assertion language and specify a rule based validation language that is not identical to, but intersects with ISO Schematron. This new Schematron language has the advantage of roughly 15 years of development in markup technology and roughly 15 years of ISO Schematron practice.

It should be based on the XQuery and XPath Data Model 3.1 [WALSH2017], a data model that includes maps, arrays, and support for strongly typed languages with a type system. It should also distinguish between a core specification and language extensions, and describe an extension mechanism that decouples the core from query language or use-case specific extensions such as streaming validation [DZIURLAJ2021] or interactive corrections [KUTSCHERAUER2018]. Given the rise of JSON [JSON] it should try to align with jsontron [AMER2014] and provide a query language binding for JSON-based path languages.

Most importantly, it should again be an Open Standard.