[XeTeX] Assignment of codes (particularly \catcode) based on Unicode data

[David Carlisle]

On 6 May 2015 at 20:15, Philip Taylor <P.Taylor at rhul.ac.uk> wrote:
>
>
> Apostolos Syropoulos wrote:
>
>> It seems to me that most people have no idea what Unicode is and what is really
>> involved.
>
> OK, so if we restrict the Universe of Discourse to the set of native
> Hellenic speakers who know what Unicode is, know the importance of being
> able to use it to identify the correct upper case of (for example)
> 'GREEK SMALL LETTER EPSILON WITH PSILI', and hold an informed opinion on
> the matter, would you expect that 100% of these would agree that the
> uppercase is 'GREEK LETTER EPSILON' and not 'GREEK LETTER EPSILON WITH
> PSILI', or would you expect that some percentage (perhaps small) would
> hold the opposite point of view ?
>
> ** Phil.
>

I don't think that's the right question. Even if everyone, including
the Unicode technical committee,
agreed some properties are incorrect for some characters, it isn't
clear we should change
them at this level.

I think that unicode-letters.def makes most sense as a
fully automated representation of the UCD data files in TeX syntax.

That way everyone knows what data is in there.

Individual language packages have far fewer characters to worry about
and can over-ride
the base settings where appropriate.

David

[Joseph's original message was cross posted to luatex list,
is there a particular reason that has been dropped?
it seems unfortunate as  a major part of the question was
how to arrange to get the same settings on both systems]