Re: ligature usage - WAS: How do we find out what assigned code points aren't normally used in text?

2011/9/11 Michael Everson <everson_at_evertype.com>:
> On 11 Sep 2011, at 00:23, Richard Wordingham wrote:
>
>> A font need not support such ligation, but a glyph for U+FB01 must
>> ligate the letters - otherwise it's not U+FB01!
>
> Not in monowidth, it doesn't.

I also agree, a monospaced font can perfectly show the dot and ligate
the letters, using a "double-width" (2em) ligature without any
problem, or simply not map it at all, or choose to just map a
composite glyph made of the 1em-width glyphs assigned to the two
letters f and (dotted) i without showing any visible ligation between
those glyphs (this being consistant with monospaced fonts that remove
all ligations, variable advances and kernings between letters).

You could as well have a font design in which all pairs or Latin
letters are joined, including in a monospaced font, in which case you
should not see any difference between FB01 and the pair or Basic Latin
letters. Joining letters is fully independant of the fact that the
upper part of letter f may or may not interact graphically with the
presence of a dot. If the style of letter glyphs does not cause any
interaction, there's no reason to remove the dot over i or j in the
"ligature" or joining letters.

You should not be limited by the common style used in modern
Times-like fonts (notably in italic styles, where the letter f is
overhanging over the nearby letters). Other font styles also exist
that do not require adjustment to remove the dot, or merge it with a
graphic feature of the preceding letter f which is specific to some
fonts.

As the pair of letters f and (dotted) i is perfectly valid in Turkish,
there's absolutely no reason why the fi ligature would be invalid in
Turkish. But given that this character is just provided for
compatibility with legacy encodings, I would still not recommand it
for Turkish or for any other language, including English. This FB01
character is not necessary to any orthography and if possible, should
be replaced by the pair of Basic Latin letters (and in fact I don't
see any reason why a font would not choose to do this everywhere)

-- Philippe.
Received on Sun Sep 11 2011 - 00:38:38 CDT