Re: [ddlm-group] [THREAD 4] UTF8

---

From: Herbert J. Bernstein <yaya@bernstein-plus-sons.com>
To: Group finalising DDLm and associated dictionaries <ddlm-group@iucr.org>
Sent: Friday, 23 October, 2009 20:47:40
Subject: Re: [ddlm-group] [THREAD 4] UTF8

Dear Colleagues,

  I have only mild objections to saying the "UTF-8 is the only official
encoding for CIF 2".  My mild objection is that imgCIF will not be
compliant in sereral of its variants, but it certainly will always be able
to provide at least one compliant translation of any file, 50-60% bigger
than it has to be in, say, UCS-2, but compliant.

  No, the real problem is not what is officially the "right" way to write
CIFs, but what people will really do.  People will do what they have
always done -- work with CIF on whatever system they have.  That system
may be modern and support UTF-8, but, even then, its "native" mode may be
something different.  If we are lucky, the differences will be
sufficiently dramatic to allow the encoding used to be detected from
context.  If somebody decides they are still using EBCDIC, we will have no
trouble figuring that out, but sometimes the differences are more subtle.
I just took a French message catalog for RasMol and converted it to the
Latin-1 encoding.  Most of the text is absolutely the same.  Just a few
acented characters differ.  In a large text with just a few accents, this
could easily be missed, and lots of people in Europe use the Latin-1
encoding.  I am not saying that we should handle Latin-1 in all CIF-2
parsers.  I am saying that it would be a very good idea to conform to the
vim or emacs editor conventions in marking CIF with their encoding, so
that if somebody does make a mistake and send a journal a Latin-1 CIF-2
file instead of a UTF-8 CIF-2, there will be some chance of spotting the
error.

The is the same issue as having the magic number #\# CIF 2.0 so we have a
chance to spotting cases where somebody is trying to feed in a different
CIF level.  Just because somebody might, somewhere, sometime, decide to
send in a file to a CIF 1 parser with a magic number such as #\# CIF 2.0
does not mean that suddenly we have to tell the person with the CIF 1
parser that their parser is broken.  It just means the person with the CIF
1 parser or the person with the CIF 2 file have a better chance of quickly
figuring out they have a mismatch.

People will edit in different encodings, whether we approve of it or not.

We lose nothing by flagging the UTF-8 encoding, and we can save people a
lot of time in the future.

Regards,
  Herbert

=====================================================
  Herbert J. Bernstein, Professor of Computer Science
    Dowling College, Kramer Science Center, KSC 121
        Idle Hour Blvd, Oakdale, NY, 11769

                  +1-631-244-3035
                  yaya@dowling.edu
=====================================================

On Fri, 23 Oct 2009, David Brown wrote:

> I would just like to point out a philosophical principle which we tried to
> observe in the earlier CIFs, and which I think very important, namely that in
> a standard like CIF it is only necessary to define one convention for each
> feature in the standard.  Writers are required to convert the input to this
> convention and readers can always be confident that they will only have to
> read this one convention.  Every time you allow alternative ways of encoding
> a piece of information you *require* the reader to be able to read both
> alternatives.  If you allow three different encodings, you require three
> different parsers.  If you allow ten different codings, you require ten
> different parsers in every piece of reading software.  With one standard, a
> single parser works everywhere.
>
> If a standard allows two different codings, it is no longer a standard, it is
> two standards, and that is something we have tried to avoid (not always
> successfully) in CIF.  It should be a goal.
> David
>
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