LISTSERV mailing list manager LISTSERV 16.0

Help for LATEX-L Archives


LATEX-L Archives

LATEX-L Archives


LATEX-L@LISTSERV.UNI-HEIDELBERG.DE


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Proportional Font

LISTSERV Archives

LISTSERV Archives

LATEX-L Home

LATEX-L Home

LATEX-L  June 2001

LATEX-L June 2001

Subject:

Re: \InputTranslation

From:

Chris Rowley <[log in to unmask]>

Reply-To:

Mailing list for the LaTeX3 project <[log in to unmask]>

Date:

Tue, 5 Jun 2001 13:29:19 +0100

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (175 lines)

Marcel wrote (very wisely):

> I'd like to bring the discussion back to the ICR issue, in
> particular how a hypothetical successor to TeX should handle
> input encodings.

The subsequent discussion led me to write the following, which does
not say in fact say much about input encodings; I hope that the reason
for this omission becomes clear to those who read further.


chris


Part the First:

First, I regret to say, some general theory about text characters and
languages.

Note that the ICR is a Character Representation, in the sense defined
in
the Unicode standard, and not a glyph representation or an Enhanced
Character Representation, ie one in which each `character' contains
more
information than simply its name(encoded).

A string in such an ICR is useful because it is a standardised
representation in which each character representation has a fixed
meaning \emph{as a character}.

BUT, for all the many reasons given in this discussion and several
others, having nothing more than such strings is inadequate for many
of the sub-processes involved in a typical document-processing system.
A complete analysis of these processes and the information they
require is probably not feasible and certainly not useful since they
change rapidly with the requirements of document processing.  The
only thing that can be said is that further information about these
strings must be accessible by the sub-processes of the system.

Therefore, rather than attempting to categorise the necessary
information and devise suitable ways to provide it, Frank and I came
up with the idea of simply supplying a single logical label for every
ICR string.  Since the first, and still the overwhelmingly most
diverse,
parts of this information came from the needs of multi-lingual
documents, we called this label the `language' (maybe not a good
choice).  Our thesis is that `every text string must have a
language-label'.  The only property these labels need (and indeed are
able) to have is that they \emph{can} help any application or
sub-process to access the information it needs to process that text
string.

From this it follows that all applications and sub-processes must also
ensure that this language-label is preserved with all text strings to
which it applies (ie no text string ever goes anywhere without its
language-label).  In a (near) mono-lingual document it may not be
necessary to explicitly supply the label if that label is the
document's main language but this is a (possibly non-robust)
implementation efficiency.

[In order to distinguish these logical language-labels from anything
else in the TeX world let us call them LLLs.]

In the context of current TeX-related systems this
means that:

-- whenever a character token list (in an ICR) is constructed or
   moved, then its LLL must go with it;


Part the Second:

So what does this mean for an ICR for a potential TeX/Omega?

First the simple case, in which everything that is encoded in the ICR
is `strongly internal': it is never seen in external files or passed
to
external applications.

It means that all ICR strings, and hence all token lists potentially
containing text, must have an LLL.


Thus to take one small example, based on Javier's:

  \newcommand{\foo}{\unichar{<Unicode code>}}

is what is needed simply to get something that expands to the single
ICR character :

  \unichar{<Unicode code>}

or it may expand further to a single (Unicode-encoded character) token
(the choice being made according to whether one is still restricted to
8-bit internals etc).

Since this character is used in widely distinct languages, in order
to use this within Mandarin you would then, I guess, need to put
something like this in your document:

  \begin{mandarin}
    ... \foo{} ...
  \end{mandarin}

or  \mandarintext {... \foo{} ...}.


But if you want \foo to be exclusively a bit of Mandarin text then you
could (or even should) define something like (syntax is probably
dreadful):

  \newcommand{\foo}{\languageIC{manadrin}{\unichar{<Unicode code>}}}

How clever the expansion of \languageIC needs to be will depend on how
such input will be used.


Part the Third:

All of the above is completely independent of what input scheme is
used, except that defining things like \foo defines part of a 7-bit
input scheme.  All such inputs, and all other input encodings, must at
first input time be normalised to their unique representation in the
ICR(*).  To this ICR representation of a text string, an LLL will need
to be added, explicitly or implicitly.

IMPORTANT: After that first time input conversion the input encoding
that was used is unknown and not needed; this is a vital property of
our ICR model.

(*) This could be done by several methods, depending on the
application doing it; within Omega the following will, we hope, be
available: input-translation; expansion; character-token-list OTPs.


Part the Fourth:

Unfortunately, in a multi-pass system such as LaTeX the LICR is not
`strongly internal': information that is internal to LaTeX must be
stored in external files.  If these could be made effectively internal
then this would not be a problem but there are two difficulties with
that approach:

-- although not explicitly, current LaTeX makes these files readable
   and editable (at least by English users:-);

-- very similar information is written out for use by other
   applications.

[Note that here I am not thinking of writing to the terminal since
that
is a one-way process and the output is useless if not immediately
comprehensible (it is thus a really tricky problem).  The status of
the log file is unclear (I would perhaps treat it like the terminal).]

Thus this leads directly to these questions (two, since different
choices may be needed):

1.  How should LICR strings be written out to files used only by LaTeX
    itself?

2.  How should LICR strings be written out to files read by other
    applications?

My feeling is that the answer to 1. should, if possible, be something
independent of any input schemes in use.

It is not so clear that this is possible for 2. and there may be good
reasons why these two outputs should be the same.


Part the Fifth:

So have I removed the question: "do we need to record the input
encoding?"?  Or merely cleverly hidden it?

Top of Message | Previous Page | Permalink

Advanced Options


Options

Log In

Log In

Get Password

Get Password


Search Archives

Search Archives


Subscribe or Unsubscribe

Subscribe or Unsubscribe


Archives

September 2019
July 2019
April 2019
March 2019
February 2019
January 2019
December 2018
November 2018
October 2018
September 2018
August 2018
June 2018
May 2018
April 2018
February 2018
January 2018
December 2017
September 2017
August 2017
July 2017
June 2017
May 2017
April 2017
March 2017
February 2017
January 2017
December 2016
July 2016
April 2016
March 2016
February 2016
January 2016
October 2015
September 2015
August 2015
July 2015
June 2015
May 2015
April 2015
March 2015
February 2015
January 2015
December 2014
November 2014
October 2014
September 2014
August 2014
July 2014
June 2014
May 2014
April 2014
March 2014
February 2014
January 2014
December 2013
November 2013
October 2013
August 2013
July 2013
June 2013
May 2013
April 2013
March 2013
February 2013
January 2013
December 2012
November 2012
September 2012
August 2012
July 2012
June 2012
May 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
November 2010
October 2010
September 2010
August 2010
July 2010
June 2010
May 2010
March 2010
February 2010
January 2010
December 2009
November 2009
October 2009
September 2009
August 2009
July 2009
June 2009
May 2009
April 2009
March 2009
February 2009
January 2009
December 2008
November 2008
October 2008
September 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
September 2007
August 2007
June 2007
May 2007
March 2007
December 2006
November 2006
October 2006
August 2006
July 2006
June 2006
May 2006
April 2006
March 2006
February 2006
November 2005
October 2005
September 2005
August 2005
May 2005
April 2005
March 2005
November 2004
October 2004
August 2004
July 2004
May 2004
April 2004
March 2004
February 2004
January 2004
December 2003
October 2003
August 2003
July 2003
June 2003
May 2003
April 2003
March 2003
February 2003
January 2003
December 2002
October 2002
September 2002
August 2002
July 2002
June 2002
March 2002
December 2001
October 2001
September 2001
August 2001
July 2001
June 2001
May 2001
April 2001
March 2001
February 2001
January 2001
December 2000
November 2000
October 2000
September 2000
August 2000
July 2000
May 2000
April 2000
March 2000
February 2000
January 2000
December 1999
November 1999
October 1999
September 1999
August 1999
May 1999
April 1999
March 1999
February 1999
January 1999
December 1998
November 1998
October 1998
September 1998
August 1998
July 1998
June 1998
May 1998
April 1998
March 1998
February 1998
January 1998
December 1997
November 1997
October 1997
September 1997
August 1997
July 1997
June 1997
May 1997
April 1997
March 1997
February 1997
January 1997
December 1996

ATOM RSS1 RSS2



LISTSERV.UNI-HEIDELBERG.DE

Universität Heidelberg | Impressum | Datenschutzerklärung

CataList Email List Search Powered by the LISTSERV Email List Manager