Carlos Perez, again (third in a row):
The beauty of Schematron is that a document is valid for only the parts that the recieving application is interested in. Everything else is effectively ignored. If you really think about this, it’s actually the right way. Just ask postel who said “Be liberal in what you accept”.
In a world of asynchronous communication, certain pieces of information arrive to your node that just happens to be there because its actually in transit. Assuming that every node has global knowledge and agreement as to what goes in every message that it comes across is simply asking to boil the ocean’s water.
I whole-heartedly agree; considering an earlier posting of yours truly, it’s small wonder that I find Schematron hugely attractive.