W3C home > Mailing lists > Public > www-tag@w3.org > June 2007

What "ignore" means (was: RE: Defined sets, accept sets, and <banana> elements)

From: <noah_mendelsohn@us.ibm.com>
Date: Mon, 25 Jun 2007 14:18:02 -0400
To: "David Orchard" <dorchard@bea.com>
Cc: "Tim Berners-Lee" <timbl@w3.org>, www-tag@w3.org
Message-ID: <OFA2CBBAB1.79CCEE8F-ON85257305.006314B5-85257305.00648848@lotus.com>

Dave,

> I agree that the definition of "ignore" needs elaboration.

As we discussed on the TAG call a few minutes ago, I think you're 
focussing on just the right question, though I remain unsure that "ignore" 
will in most cases be the most appropriate word.  Repeating what we said 
there, my intuition is that "accept" is about the right word to describe a 
text that is consumable by some application or conformant with some 
specification.   I think many languages provide generic semantics for 
handling content that is not explicitly described (whitespace, comments, 
extension elements, diffferences in text that are not significant, etc.) 

Here's a use case I mentioned in passing.  I think it's a common one, and 
a good test of our terminology.  Consider a name language in which, in 
version 1, the case of the input (I.e. upper or lower case) is no more (or 
less) relevant than <banana> elements in HTML.  So:

        name1.nam:
 
        bob smith

is for most purposes semantically equivalent to 

        name2.nam:
 
        Bob Smith

I say for the most part, because just as the HTML DOM allows you to see 
<banana> elements, the V1 specification for my language says:

"Case is in general not significant in version 1 of this language.  A 
keyword such as APPLE is generally treated the same way as apple. However, 
when displaying, printing or storing the text of a document, applications 
SHOULD preserve the supplied case.  Note:  it is possible that subsequent 
versions of this language specification will consider case to be 
significant.  Accordingly, version 1 documents SHOULD be created as lower 
case only (indeed, applications receiving mixed or uppercase documents may 
assume that they were created by software written to later versions of 
this specification.)"

So, I'd say that's a good example of future proofing.  If the defined set 
is lowercase, then each acceptable document either is in or has an 
equivalent document in the defined set.  The interesting question is: 
what's being ignored?  It's certainly not any of the characters.  While it 
so happens that in some encodings, case is a separate bit, we can't assume 
that. 

Note that when we talk about generic semantics, the story gets easier than 
if we're looking for something to ignore.  The generic semantics is: 
retain case for printing, storage, etc., and otherwise treat as if 
uppercase is mapped to lowercase. 

I think it would be good if our terminology were suitable for such forms. 
First of all, they're simple and quite common.  Secondly, it's a good way 
to make sure we haven't slipped in assumptions we didn't intend. 

Anyway:  I'm really glad we're starting to look more carefully at the 
assumptions behind "ignore".  I've always felt that to be where the meat 
of the problem is.  Thanks!

Noah

--------------------------------------
Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
1-617-693-4036
--------------------------------------








"David Orchard" <dorchard@bea.com>
06/21/2007 04:59 PM
 
        To:     <noah_mendelsohn@us.ibm.com>
        cc:     "Tim Berners-Lee" <timbl@w3.org>, <www-tag@w3.org>
        Subject:        RE: Defined sets, accept sets, and <banana> 
elements


I agree that the definition of "ignore" needs elaboration.  I think
there are at least 2 major flavours: ignore and delete, and ignore and
retain. 

Given that you agree that "weaving" is a good next step, what do you
think about "weaving" by reference to a micro-finding rather than
weaving into the text? 

Cheers,
Dave 

> -----Original Message-----
> From: noah_mendelsohn@us.ibm.com [mailto:noah_mendelsohn@us.ibm.com] 
> Sent: Thursday, June 21, 2007 1:01 PM
> To: David Orchard
> Cc: Tim Berners-Lee; www-tag@w3.org
> Subject: RE: Defined sets, accept sets, and <banana> elements
> 
> David Orchard wrote:
> 
> > I had an action item, either official or unofficial, to 
> weave a story 
> > like this into the finding.  I suggested to you and the tag 
> that your 
> > material could be either incorporated into the finding or as a 
> > separate micro-finding, and that I'd do any extra work 
> required.  You 
> > didn't support either of those options,
> 
> To be clear, you are welcome to "weave" what I wrote into the 
> finding if you think that's the right next step.  I was 
> merely suggesting a direction that I thought would be 
> interesting, and that would involve doing a bit more 
> investigation and consensus building before we decide what to 
> put in the finding.  One way or the other, I strongly believe 
> that we need to think hard about, and probably tell a story 
> in the finding about, languages which have semantics other 
> than "ignore" for extension content. 
> By all means, if you think my email is the right basis for 
> telling that story, then integrate it, and we'll see what the 
> reaction is.  Sorry if my original email was confusing.
> 
> --------------------------------------
> Noah Mendelsohn
> IBM Corporation
> One Rogers Street
> Cambridge, MA 02142
> 1-617-693-4036
> --------------------------------------
> 
> 
> 
> 
> 
> 
> 
> 
> "David Orchard" <dorchard@bea.com>
> 06/21/2007 03:17 PM
> 
>         To:     <noah_mendelsohn@us.ibm.com>
>         cc:     "Tim Berners-Lee" <timbl@w3.org>, <www-tag@w3.org>
>         Subject:        RE: Defined sets, accept sets, and <banana> 
> elements
> 
> 
> I had an action item, either official or unofficial, to weave a story
> like this into the finding.  I suggested to you and the tag that your
> material could be either incorporated into the finding or as 
> a separate
> micro-finding, and that I'd do any extra work required.  You didn't
> support either of those options, so I'm not interested in duplicating
> such work by completing my action using separate material.
> 
> Cheers,
> Dave
> 
> > -----Original Message-----
> > From: noah_mendelsohn@us.ibm.com 
> [mailto:noah_mendelsohn@us.ibm.com] 
> > Sent: Thursday, June 21, 2007 12:14 PM
> > To: David Orchard
> > Cc: Tim Berners-Lee; www-tag@w3.org
> > Subject: RE: Defined sets, accept sets, and <banana> elements
> > 
> > David Orchard writes:
> > 
> > > I had an action item, either official or unofficial, to 
> > weave a story 
> > > like this into the finding.  I think that action is now closed..
> > 
> > Well, I've suggested a direction for deciding what to do, but 
> > it's just my opinion.  Are you suggesting that you are going 
> > to go through the steps I suggested and update the finding 
> > depending on what results?  Thanks.
> > 
> > Noah
> > 
> > --------------------------------------
> > Noah Mendelsohn
> > IBM Corporation
> > One Rogers Street
> > Cambridge, MA 02142
> > 1-617-693-4036
> > --------------------------------------
> > 
> > 
> > 
> > 
> > 
> 
> 
> 
Received on Monday, 25 June 2007 18:18:19 UTC

This archive was generated by hypermail 2.3.1 : Wednesday, 7 January 2015 15:32:52 UTC