[XTAN] A limited extensibility mechanism (but extensible)

All,

Trying to find a resolution to the "object VS frame" discussion, that would reconcile the requirement for maximal interoperability between PRD and Core, and the demand for dialect-specific idioms (as part of the requirement for easy implementability and wide adoptability), I came back to exploring the feasibility of some kind of simple extensibility mechanism...

And I came to two conclusions:
- There is a quite simple solution, using XSLT, that enables a form of limited forward compatibility between extended and extending dialects;
- Such a mechanism is desirable even if we do not add new specific syntax to what PRD already has (for several reasons, but one, with which  I expect everybody will agree, is scalability).

I wrote a strawman proposal [1], with a couple examples, and I tried a complete, if simple, example to check feasibility. You will find attached:
- a file called PRDex.xml, that contains a PRD-fied version of the complete example in BLD;
- a file called COREex.xml, that contains a COREified version of the same;
- a file called do2and.xsl, that contains the XSLT stylesheet that I used to produce COREex.xml from PRDex.xml (I tested it with msxsl and saxon9).

[1] http://www.w3.org/2005/rules/wiki/Limited_Forward_Compatibility

What makes me believe that the solution I propose is simple, is that I did not know anything about XSLT only 10 days ago, and I believe, now, that I could write, in a matter of days, the complete XSLT stylesheet for all the fallbacks needed to provide limited forward compatibility to Core wrt PRD as it stands today (and some more :-)

Does this make sense?

Cheers,

Christian