Keeping meaning local

Standardize the minimum necessary XML provides a useful set of standards without (much of) a vocabulary. Standardizing layers on top of XML may reduce friction in some cases, but may do so at the cost of stifling potentially useful semantic innovation. ISO standardizes shipping containers, not their contents. (The fear of Microsoft is not enough reason to standardize the world defensively.)
Acknowledge and encourage diverse processes By modeling current document processes, where standardization and customization interact on a regular basis, we may have enough diversity that new things - especially new error conditions - can emerge and be appreciated/fixed.
Give local control over semantics However much communities share, local interpretation remains a critical issue. In the end, what matters is whether individual transactions work, not whether they use the same mechanism to get there.
Learn from new events Processes evolve, and businesses change. Just-in-time didn't exist in Japan forty years ago, or in the U.S. twenty years ago. Assuming that we've learned all there is to know, or even most of it, is dangerous.