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[F&O] 14.1.5 fn:lang

From: David Carlisle <davidc@nag.co.uk>
Date: Mon, 17 Nov 2003 15:22:18 GMT
Message-Id: <200311171522.PAA30898@penguin.nag.co.uk>
To: public-qt-comments@w3.org


The informal description has a couple of instances of 
"then returns false." 
which would probably read better as "then the function returns false"
as otherwise there doesn't appear to be a subject.

 
> If $lang is the empty sequence it is interpreted as the zero-length string.

This should presumably be $testlang as there is no parameter called
$lang in the function signature.

> (The character "-" is HYPHEN-MINUS, %x002D) 

The syntax %x002D isn't used elsewhere, I suspect that #x002D is meant,
as that is used in other places to denote a character by hex unicode
value.

The relevent attribute is unambiguously specified by an Xpath expression
but the equality test used is described by a rather contorted (and
perhaps under specified) prose description. It would be clearer if
function was specified in its entirety by an Xpath expression,

something like

fn:upper-case(fn:replace((ancestor-or-self::*/@xml:lang)[last()],'-.*',''))
=
fn:upper-case($testlang)


using an explict expression (specified as using unicode codepoint
collation) such as the above would make it clearer what is meant by the
current wording "ignoring case".

If "ignoring case" means first uppercase then compare then

dotless i would compare equal to i
and
ess-zed would compare equal to SS

however if "ignoring case" means first lowercase then compare
then both of the above two comparisons would compare non-equal.

I don't think the current wording defines which of these (or other
possible interpretations) should be used.


Alternatively (and perhaps preferably) "ignoring case" should be
replaced by an explict reference to
1.3 Caseless Matching
in the Unicode case mapping appendix (TR 21).


Note however that the current normative reference to Tr21 in F&O is to
http://www.unicode.org/unicode/reports/tr21/ 
however that page just says

  Superseded Technical Report

  UAX#21: Case Mappings has been incorporated into the Unicode Standard
  Version 4.0, and is thus now superseded. The last version of that
  document before it was superseded can be found at
  http://www.unicode.org/reports/tr21/tr21-5.html

So it might be better to make the normative reference be Unicode 4, with
a non-normative reference to tr21-5, for the benefit of those of us
without a unicode 4 book.


David


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Received on Monday, 17 November 2003 10:26:17 GMT

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