> Is it not possible to make SCM's alignment with both OM-n and maybe other > non-OM formalisations 'dynamic'?
yes of course but at a cost. We could (taking it to extremes) declare the content type of every element to be open and any attributes to be allowed, and just state that MathML defines the semantics for a range of expressions and that any other expressions are nt invalid but are curently undefined in mathml3. This allows arbitrary future extension but gives up on any error checking or schema context driven editing help on current documents. In practice of course you end up doing someting in between and making each construct open or closed depending on its merits as you see it, but the tradeoffs are not really so different in each case. But the OM design really is for a fixed stable set of primitives with exteibility being by the CD mechanism specifically so it doesn't require XML level schema changes to extend. That's not to say that OM shouldn't be extended occasionally but that should be rather more rare than most XML vocabularies. In particular every MathML exression is supposed to have a default rendering so the more you open up the schema the more you have to specify (or wave hands to avoid specifying) what some arbitrary construct is supposed to look like. David ________________________________________________________________________ The Numerical Algorithms Group Ltd is a company registered in England and Wales with company number 1249803. The registered office is: Wilkinson House, Jordan Hill Road, Oxford OX2 8DR, United Kingdom. This e-mail has been scanned for all viruses by Star. The service is powered by MessageLabs. ________________________________________________________________________ _______________________________________________ Om3 mailing list [email protected] http://openmath.org/mailman/listinfo/om3
