Re: [xml-dev] Extending type definitions using RelaxNG Compact

James Clark wrote:

> [...]  TREX provided a
> concur operator which would have been sufficient for this, but it didn't
> make it into RelaxNG, because there are major implementation issues.

What were the issues?

CONCUR is easy to implement in regular expressions over strings --
it's actually a bit simpler than INTERLEAVE -- does it get
tricky in tree-regular grammars?  Or was it something else?

<URL: http://lists.oasis-open.org/archives/relax-ng/200103/msg00004.html >
only mentions type assignment and coherent error messages
as problem areas.   (Personally, I'd gladly trade both for CONCUR --
you can do some neat things with it...)


--Joe English