Chromatic text, ligatures and Fraktur ligatures. (derives from Re: Chromatic text)

From: William Overington (
Date: Mon Jul 08 2002 - 05:40:40 EDT

Michael Everson wrote as follows.

>Your courtyard codes and your scientific chromatic explorations are
>not appropriate uses of the standard. With Quark XPress I can set my
>fonts to display in HUNDREDS OF THOUSANDS if not MILLIONS of colours,
.... .

Courtyard codes and chromatic fonts are, in my opinion, entirely appropriate
uses of the standard.

Recently I was referred to an ISO document about characters and glyphs,
ISO/IEC TR 15285. This is available in a zipped format as follows. It
unzips to a .pdf file.

Courtyard codes and codes for chromatic fonts, in my opinion, fall within
the definition of character in Annex B of that document. This is not me
finding some definition tucked away obscurely, it is central. The
introduction section of the document states as follows.


This Technical Report is written for a reader who is familiar with the work
of SC 2 and SC 18. Readers without this background should first read Annex
B, "Characters" and Annex C, "Glyphs".

end quote

Courtyard codes also allow the use of millions of colours. There are 18
codes for changing colour, 16 for specific colours and 2 for colour 98 and
colour 99 which can be set to any of those millions of colours using other
courtyard codes. Indeed, it is possible to use them with colours of more
than 8 bits per colour channel so that they could be used for the high
definition colour option of .png files if so desired. I may add a code into
courtyard codes to signal that use option explicitly.

Lots of programs can use millions of colours: expensive programs and widely
available programs. It is part of modern computing. For example the
Microsoft Paint program which can be used for preparing illustration files
using a particular set of colours chosen from the millions of colours which
the Paint program can be used to produce. There is an article about such a
use in relation to preparing artwork for broadcasting upon the DVB-MHP
(Digital Video Broadcasting - Multimedia Home Platform) system at the
following address.

Courtyard codes are, in my opinion, very important for the future of
broadcasting using the DVB-MHP system. They will enable Unicode text files
to carry colour and formatting information which can be straightforwardly
interpreted by a variety of relatively small Java programs from a variety of
content providers. The advantages for the broadcasting of educational
multimedia across whole continents will be enormous if a consistent set of
codes for colours and basic formatting is widely used in a consistent
manner. Certainly if such a set were provided in plane 0 of regular Unicode
then that would be magnificent, yet in any case, that takes time and the
need to gain a consensus as to the use of a particular set of codes is now,
and courtyard codes are, as far as I am aware, the only set of codes
available to do the job at the present time.

>If you can't support Unicode on older
>systems then that's because the systems aren't good enough.

Ah! A digital divide issue. Windows 95 and Windows 98 systems, which are
not very old at all, cannot, as far as I am aware, support advanced font
technology such as OpenType. In addition, these advanced font technologies
are not part of the international standards and it seems to me that it is a
good thing for Unicode to provide facilities for advanced font usage, yet
quite another thing to start cutting off support routes for users of older
equipment, even when that equipment is only three years old.

> Are PUA
>hacks to fix that a productive use of energy? One can't support
>everything in legacy data.

You appear to be referring to my definition of the golden ligatures
collection. Well, first of all, I feel that the word "hack" is
inappropriate. The golden ligatures collection is a published list of
Private Use Area allocations. The documents clearly state what they are and
what they are not.

The fact of the matter is that people who vote on these matters, largely
only having a vote because they are the representatives of large
corporations, have decided that no more precomposed ligatures will be added
into Unicode. I have accepted that that was the situation in which we find
ourselves and that it is pointless seeking to get the decision changed, so I
have settled for the fact that they have made the decision and I have
published the golden ligatures collection and if the golden ligatures
collection gets widely used, then good. Since you raise the matter,
however, I do feel that adding U+FB07 as a ct ligature would be useful and,
indeed, the golden ligatures collection is designed so that the chosen code
points dovetail nicely with the code points of the U+FB.. block of regular
Unicode: the issue seems more one of the politics of simply ignoring the
needs of people who are not using the very latest equipment, for I feel that
the committees could quite easily include those ligatures if they wanted to
do so, the amount of additional programming for software systems to be able
to decompose them is perhaps not too great if someone has already programmed
decomposition of the seven existing precomposed ligatures. It is simply a
political issue of providing facilities for people who are not using the
very latest equipment. One of the committees appears to be meeting in
August on four days in three rooms in two buildings in one week. How long
would it really take them to decide to add in a few extra ligature
characters into the U+FB.. block in order to resolve a problem that can only
at present be solved within the Unicode system using Private Use Area codes.
I notice that some Fraktur fonts use code points for ligatures which are not
part of the Unicode system. I would have thought that it would, on balance,
be better for the committees to review the matter and add the ligatures into
the U+FB.. block once and for all. Fraktur is not going to go away and
neither are the ligature decisions involved in typesetting Fraktur and
neither is historical research into 18th Century English printed books and
so on.

On another aspect of this matter of ligatures, I may be wrong and it may
just be me who feels this way, yet I do feel that there is perhaps a feeling
that it is nice to be able to set individual electronic units which are in
one to one correspondence with the metal units which historical printers
actually picked up out of a type tray and placed in a composing stick. I
have recently started making fonts, using the Softy program, (shareware
which is available on the web) and I do like to have a ct ligature at
decimal 59143, which is U+E707, as if it were a piece of metal type in some
sort of virtual olde worlde printshop. Is that just me or does anyone else
get that feeling too?

William Overington

8 July 2002

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