LC-97, XML Schema Last Call Issue 97: hexadecimal notation for integers

     October 8, 2000

Dear Mr. Ransom,

The W3C XML Schema Working Group has spent the last several months
working through the comments received from the public on the last-call
draft of the XML Schema specification.  We thank you for the comments
you made on our specification during our last-call comment period, and
want to make sure you know that all comments received during the
last-call comment period have been recorded in our last-call issues
list (http://www.w3.org/2000/05/12-xmlschema-lcissues).

Our records show that you raised the issue registered
in our issues list as:

LC-97. hexadecimal: Allow hex notation for integers

Below I have recorded our understanding of the issue,
some history of the discussion of the issue within the
Schema WG and our resolution.

Please read this material and the instructions following
on how you should respond with your opinion of how
satisfactory the resolution was.


LC-97. hexadecimal: Allow hex notation for integers
----------------------------------------------------
Issue Class: D Locus: datatypes Cluster: 04 numeric Status: resolved
Assigned to: Frank Olken Originator: Doug Ransom

Description
-----------

 Should hexadecimal notation be allowed for numbers
(at least for integer and non-negative integer)?

Interactions and Input
----------------------

  Cf. Allow multiple lexical spaces for floats?

Input from Doug Ransom:

Doug Ransom <Doug_Ransom@pml.com> to XML Schema Comments list,
Fri, 5 May 2000 11:53:52 -0700

I think would be very unfortunate if Integer and NonNegative integer
could not have hex lexical structure. i.e.

      0xffaa00bb instead of 4289331387.

Binary is really inapprpriate for this -- people often want
to represent numbers as hex (i..e HTML colours).

Discussion
----------

Although the Schema WG has been largely silent publicy
concerning multiple lexical representations of datatypes
(e.g., integers) such questions have been the subject of
lengthy discussions within the Schema Working
Group and with I18N (The Internationalization WG).

The Internationalization WG (I18N) has strongly urged that there
be only a single lexical representation for each datatype
and that alternative lexical forms be generated (handled)
by either stylesheet transformations (XSLT) or some other
localization mechanism.

Also, a number of schema work group members have taken a
somewhat similar position, namely, that XML is intended to
be a document/data exchange  format and that therefore a
single lexical representation is desirable to simplify
implementation and canonicalization (which is needed for
digital signatures).  Again, variant lexical representations
could be generated via XSLT.  (But this does not address input.)

Other comments included the observation that hexadecimal notation
does not increase the expressiveness of the Schema Language,
but does add complexity to the parser (lexical analyser).
A related issue was the question of how to indicate which
radix was to be used (since many hexadecimal numbers are also
legal decimal numbers).  Traditionally, this has been done
by some sort of prefix symbol (e.g. "0x"). Other alternatives discussed
included some sort attribute on the enclosing element tag
(but that does not work for attribute values).  The opposition
to simply prefix symbol was that it did not address the general
question of alternative lexical representations (e.g. European
conventions on using commas for decimal points).

The Schema Working group did eventually tentatively adopt a proposal
for abstract datatypes, which would have pemitted multiple lexical
representations.  There was even an internal draft version of
the Schema specificatio prepared.  However, it was eventually
decided to drop the abstract datatypes proposal for
Version 1.0 of Schema, because it was viewed as too complex
to finish in the context of the schedule we had set for release.

Actual Resolution
-----------------

The issue was discussed at the Edinburgh Face-to-Face meeting.

The general tide of comments has run against allowing multiple
lexical forms for the same type, even to the point that some
comments criticize the decision to allow leading zeroes for integers.
So the WG believes this would not be a wise change.

In discussions of issue LC-21, a proposal was  made for a
built-in abstract type corresponding to each of the major
existing built-in types, to allow derivation of types which
share a value space with the existing built-in type
but use a different lexical form.
If we had adopted abstract datatype proposal (see discussion above),
then schema authors could specify
hex notation for integers, though schema processors would not be
Thus, the final resolution of issue LC-97 for version 1.0 of Schema
Language was to to reject hexadecimal lexical representation of integers

for version 1.0 of the Schema Language.

Is this response adequate ?
------------------------------

The XML Schema Working Group wants to know your opinion
of our response to your last call comments.  This information
will be included with the package submitted to the W3C
Executive Director as part of the recommendation to take
the XML Schema Language to Candidate Recommendation.
We would appreciate your response as soon as possible.

Please choose from one of the following responses, adding
whatever details, explanation you wish:

1)  "GOOD ENOUGH"  - You are satisfied with the Schema WG response
to your comments on XML Schema Language.  The response meets
your requirements.  The matter may be considered resolved.

2) "STOP THE PRESSES"  - You are not happy with the response
to your comments on XML Schema Language.  Either the response
is unclear or inadequate.  The issue is of sufficient importance
and urgency that you want it called to the attention of the
W3C Executive Director and you ask that the XML Schema Language
delayed in advancing to Candidate Recommendation until the
issue is resolved.

3)  "LATER - VERSION 1.1"  - You are not happy with the response,
but are prepared to defer reconsideration until XML Schema Lang.
Version 1.1 is drafted.  It is anticipated (hoped) that Version 1.1
will be completed by mid-2001.  Version 1.1 is intended primarily
to fix small issues needed by other W3C Working Groups to proceed
with their work (especially XML Query Language).  You request that
your comments be reconsidered when drafting the Version 1.1
requirements document.

4) "LATER - VERSION 2.0"  - You are not happy with the response,
but are prepared to defer consideration until XML Schema Language
Version 2.0 is drafted.  It is anticipated that Version 2.0 would
not be completed until late 2001 or early 2002.  Version 2.0 may
include major revisions, e.g., multiple inheritance, etc.
You request that your comments be reconsidered when drafting the
Version 2.0 requirements document.

5) "NO LONGER CARE"  - You are not happy with the response, but
no longer care to pursue the matter, because ....

                  Belatedly,

                  Frank Olken
                  XML Schema Language Working Group

  Lawrence Berkeley National Laboratory   (510) 486-5891 (voice)
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Received on Sunday, 8 October 2000 18:19:00 UTC