I had a striking conversation with a colleague  yesterday.

He said he needed to add a constraint to a Schematron schema to check for some uniqueness constraint on a value.  He has not been a developer for many years, and never an XSLT/XPath/Schematron developer, and his in-house Schematron developer had left for the day.

On impulse, he asked ChatGTP for a Schematron schema to check uniqueness, and he reported that it gave a result with instructions, which he was able to type in directly, and it worked!

I think the reason for this is that the human-language assertion texts provides exactly the kind of simple statements that ChatGTP likes. (On this basis, you would expect that ChatGTP would not do as good a job with other schema languages which disconnect or discourage specifying both implementation and intent?)

I will get more info on the details later, but it is a pretty interesting thing.

I had previously tried ChatGTP and found that it gave really good answers to how to run a Schematron validation step by step, and how to make a simple assertion. (But it gave a word salad for what the rare attribute @flag does.)