Re: Encoding italic

Philippe Verdy wrote,

>> ...[one font file having both italic and roman]...
> The only case where it happens in real fonts is for the mapping of
> Mathematical Symbols which have a distinct encoding for some
> variants ...

William Overington made a proof-of-concept font using the VS14 character
to access the italic glyphs which were, of course, in the same real
font.  Which means that the developer of a font such as Deja Vu Math TeX
Gyre could set up an OpenType table mapping the Basic Latin in the font
to the italic math letter glyphs in the same font using the VS14
characters.  Such a font would work interoperably on modern systems. 
Such a font would display italic letters both if encoded as math
alphanumerics or if encoded as ASCII plus VS14.  Significantly, the
display would be identical.

> ...[math alphanumerics]...
> These were allowed in Unicode because of their specific contextual
> use as distinctive symbols from known standards, and not for general
> use in human languages

They were encoded for interoperability and round-tripping because they
existed in character sets such as STIX.  They remain Latin letter form
variants.  If they had been encoded as the variant forms which
constitute their essential identity it would have broken the character
vs. glyph encoding model of that era.  Arguing that they must not be
used other than for scientific purposes is just so much semantic
quibbling in order to justify their encoding.

Suppose we started using the double struck ASCII variants on this list
in order to note Unicode character numbers such as 𝕌+𝔽𝔼𝔽𝔽 or
𝕌+𝟚𝟘𝟞𝟘?  Hexadecimal notation is certainly math and Unicode can be
considered a science.  Would that be “math abuse” if we did it?  (Is
linguistics not a science?)

> (because these encodings are defective and don't have the necessary
> coverage, notably for the many diacritics,

The combining diacritics would be used.

> case mappings,

Adjust them as needed.

> and other linguisitic, segmentation and layout properties).
>
> The same can be said about superscript/subscript variants,
> ... : they have specific use and not made for general purpose texts ...

So people who used ISO-8859-1 were not allowed to use the superscript
digits therein for marking footnotes?  Those superscript digits were
reserved by ISO-8859-1 only for use by math and science?

MATHEMATICAL ITALIC CAPITAL A
Decomposition mapping:  U+0041
Binary properties:  Math, Alphabetic, Uppercase, Grapheme Base, ...

SUPERSCRIPT TWO
Decomposition mapping:  U+0032
Binary properties:  Grapheme Base

MODIFIER LETTER SMALL C
Decomposition mapping:  U+0063
Binary properties:  Alphabetic, Lowercase, Grapheme Base, ...
Received on Sun Feb 10 2019 - 09:32:27 CST