Re: Latin ligatures and Unicode

From: John Jenkins (jenkins@apple.com)
Date: Sun Dec 19 1999 - 16:37:40 EST


on 12/19/99 3:54 AM, Eberhard Pehlemann at e.pehlemann@gmx.de wrote:

1. For what reasons have the glyphs mentioned in (A.) and (B.) become
Unicode characters?

2. Will other latin ligature glyphs like ch, ck, sch and so on also become
Unicode characters in the future? Should I submit such a proposal? (I feel
that this would be the worst way of handling ligatures.)

3. How should people who create or use blackletter fonts handle the
ligatures mentioned above? Should they (in their text documents) e.g. code c
and h as two characters, separated by a zero-width-joiner (U+200D ZERO WIDTH
JOINER) or zero-width-ligator (as proposed by ISO/IEC JTC1/SC2/WG2 in
document N2141) and access the desired glyph from an OpenType font file
using the corresponding tables in that file?

4. What is the future of handling latin ligatures with Unicode?

1. I forget the precise reason for adding a short long-s, but it wasn't for
English of for Fraktur type. The Latin ligatures are there for
compatibility with other character sets and their use is discouraged.

2. No. It would happen only over several people's dead bodies. Please
don't submit a proposal.

3. There is a proposal to add a ligator character to specify the ligation
of two Latin characters, but the proposal is controversial.

In any event, your case wouldn't be appropriate for such a use -- you're
dealing with a number of ligatures which are compulsory within a specific
typeface. Forcing the user to specify the formation of these ligatures
whenever the characters are used -- and risking their showing up in other
typefaces where they may not be appropriate -- isn't the best way to go.
For situations where graphic alterations of the characters are required for
proper display, the Unicode approach is to have the rendering software
handle it.

In this case, it's possible to specify via either OpenType or Apple Advanced
Typography (AAT) tables in a TrueType font that such ligatures are required
when using your font. Applications which take advantage of these
technologies will do the right thing. (For the record, you can also specify
required ligatures in Metafonts for use with TeX.)

4. As I say, there's a proposal for adding a ligation control character,
but not everybody likes the idea. Which ligatures are appropriate for use
is too typeface-specific in Latin to have a general solution in plain text
IMHO.

=====
John H. Jenkins
jenkins@apple.com
tseng@blueneptune.com
http://www.blueneptune.com/~tseng



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