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Re: Comments on the WOFF Last Call

From: Chris Lilley <chris@w3.org>
Date: Tue, 8 Feb 2011 15:38:52 +0100
Message-ID: <1349220410.20110208153852@w3.org>
To: Stephen Zilles <szilles@adobe.com>
CC: "www-font@w3.org" <www-font@w3.org>
On Wednesday, January 5, 2011, 6:35:22 PM, Stephen wrote:

SZ> 2.       In the uniqueid element in the Metadata section, there
SZ> is a note:” The id attribute of the uniqueid element, and of
SZ> several further metadata elements defined below, is not required
SZ> to conform to the rules for the XML type ID; its form is at the
SZ> discretion of the font creator or vendor.” 


SZ> It does not seem
SZ> appropriate for a W3C spec to advocate violation of XML well
SZ> formedness, 

Indeed it would not! That was not the intent at all.

You seem to have read this text as "This attribute is of type ID, but its syntax is funky and not well formed" while what we were trying to say is "This attribute is NOT of type ID, so don't be misled by the name; legal values will not necessarily conform to the constraints on the ID type".

The attribute is intended to hold identifiers, such as stock numbers or build numbers, which are probably pre-existing and which may well start with numeric characters. For example


which would not be a legal value of type ID, but could easily be a legal identifier.

The spec states this:

"it is intended to allow vendors to reliably identify the exact version of a particular font."

and thus, in practice, the string "1.0" is likely to be fairly common.
SZ> especially since the uniqueid element is empty and
SZ> could contain the unique ID as its value or the some other
SZ> attribute than “id” that is less constrained might be used. 

There is no constraint on an attribute *called" id.

There are constraints on attributes of *type* ID, either declared as type ID in the DTD or schema, or inherently of that type (for example, xml:id).

SZ> Also,
SZ> the conformance requirement summary for Metadata says, “The
SZ> decompressed data MUST be well-formed XML” which seems to make the Note irrelevant.

Hopefully it should not be clear that the allowed values for @id do not make the content non-well-formed.

Indeed, one of the tests performed by the WOFF checker is to extract the XML and check that it  is well formed.

Having hopefully clarified the intention, the fact remains that the wording we used to express it has been demonstrated to be be open to misinterpretation, so we need to clarify it. The following is suggested; would it be sufficient to resolve your comment?

The id attribute of the uniqueid element, and of several further metadata elements defined below, is not of type ID. Its form is 
at the discretion of the font creator or vendor.

Tracker, this relates to
ACTION-65: Respond to Stephen Zilles re. uniqueid
Chris Lilley

 Chris Lilley   Technical Director, Interaction Domain                 
 W3C Graphics Activity Lead, Fonts Activity Lead
 Co-Chair, W3C Hypertext CG
 Member, CSS, WebFonts, SVG Working Groups
Received on Tuesday, 8 February 2011 14:38:56 UTC

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