Encoding italic

James Kass via Unicode unicode at unicode.org
Fri Feb 8 20:45:35 CST 2019

Asmus Freytag wrote,

 > You are still making the assumption that selecting a different glyph for
 > the base character would automatically lead to the selection of a 
 > glyph for the combining mark that follows. That's an iffy assumption
 > because "italics" can be realized by choosing a separate font 
 > italics is realized as a separate typeface).
 > There's no such assumption built into the definition of a VS. At 
best, inside
 > the same font, there may be an implied ligature, but that does not 
work if
 > there's an underlying font switch.

Midstream font switching isn’t a user option in most plain-text 
applications, although there can be some font substitution happening at 
the OS level.  Any combining mark must apply to its base letter glyph, 
even after a base letter glyph has been modified.

More sophisticated editors, like BabelPad, allow users to select 
different fonts for different ranges of Unicode.  If a user selects font 
X for ASCII and font Y for combining marks, then mark positioning is 
already broken.

If the user selects Times New Roman for both ASCII and combining marks, 
then no font switching is involved.  The Times New Roman type face 
includes italic letter form variants.  Any application sharp enough to 
know that the italic letter form variants are stored in a different 
computer *file* should be clever enough to apply mark positioning 
accordingly.  And any single font file which includes italic letters and 
maps them with VS14 would avoid any such issues altogether.

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