- From: Mukul Gandhi <gandhi.mukul@gmail.com>
- Date: Sat, 8 Aug 2009 15:43:50 +0530
- To: "C. M. Sperberg-McQueen" <cmsmcq@blackmesatech.com>
- Cc: www-xml-schema-comments@w3.org
Thanks, a lot for the clarification. The information would be very helpful to me. On Sat, Aug 8, 2009 at 1:58 AM, C. M. Sperberg-McQueen<cmsmcq@blackmesatech.com> wrote: > In connection with bug 7242, reported today, I have just reviewed > the text of the relevant portions of the spec; I apologize for not > doing this earlier. I should have corrected the misimpression > reported in the second paragraph quoted above: in reality, as > currently specified, inherited attributes are visible in the XDM > instances used to test conditional type assignment, but not in > the XDM instances used to test assertions. It's a natural thing > to think the two cases will be, or should be, treated the same way, > but for technical reasons the attributes used in tests for > conditional type assignment are untyped, while the WG elected to > make the attributes and descendants used in testing assertions > carry their full PSVI information, including their type assignments > and validity. In that context, including inherited attributes > would introduce some serious complications: either we would need > a story about why the type assignments are not consistent from > one instance to another, or we would need some way to ensure that > type assignments are consistent. We were able to resolve bug 5003 > successfully largely because the technique of using untyped > attributes allowed us to avoid those complications. (The treatment > of assertions would have been much simpler, too, if we had used an > untyped XDM, but the WG chose otherwise.) > > So my earlier response to your second question was misleading: > instead of saying that inherited attributes were designed to > be useful only for assertions or conditional type assignment, I > should have said: really, only for CTA. (The definition of a > term for them in the PSVI does not actually make much difference > in practice, since the information in question has always been > present in any case: any attribute among the [inherited attributes] > of an element is necessarily present among the [attributes] of > an ancestor element.) > > Sorry for not noticing this point earlier. > > -- > **************************************************************** > * C. M. Sperberg-McQueen, Black Mesa Technologies LLC > * http://www.blackmesatech.com > * http://cmsmcq.com/mib > * http://balisage.net > **************************************************************** -- Regards, Mukul Gandhi
Received on Saturday, 8 August 2009 10:14:50 UTC