From: reh2@pine.circa.ufl.edu (Rodger Hendricks)
Newsgroups: comp.fonts
Subject: Re: Re: font encoding morass
Summary: "Letterlike Symbols" are not glyphic variants
Keywords: UNICODE, character-sets, Mathematical typesetting, Zapf dingbats
Date: 27 Aug 92 22:31:50 GMT
Reply-To: reh2@pine.circa.ufl.edu
Organization: University of Florida  (ufl.edu)
News-Software: VAX/VMS VNEWS 1.3-4

In article <1992Aug21.173143.25986@adobe.com> mmwang@adobe.com (Michael Wang)
writes:
>In article <1992Aug21.054826.4016@adobe.com> delahunt@adobe.com (Jim DeLaHunt) 
>writes:
>>Unicode only pretends to provide portability of *plain text* across 
>>platforms.  Think of it as having the advantages and limitations of plain
>>ASCII text.  

>Well, perhaps the intent of Unicode is only to encode plain text, but if
>you look through some of the glyphs it does encode, I would argue they
>are there for typographical "richness". For example, look at range
>U+2100 -> U+214F. These are "letterlike" symbols including some black
>letter characters and some script characters. Or look at U+2150 -> U+218F.
>These are additional number forms including roman numerals. Then we have
>U+2460 -> U+24FF which are the enclosed alphanumerics. And of course in
>range U+2700 -> U+27BF we have all of ITC's Zapf Dingbats.

	Justifying the inclusion of "ITC Zapf Dingbats, series 100" 
in UNICODE is a task I leave to others, whom I do not envy.  The 
standard says: 

	The Zapf Dingbats differ in their treatment in the Unicode 
	standard from all other characters.  They are encoded as
	absolutely specific glyph shapes, rather than as glyphic
	archetypes for abstract characters which can be represented
	in different faces and styles.  Thus it would be incorrect to	
	arbitrarily replace U+279D TRIANGLE-HEADED RIGHT ARROW with
	any other right arrow dingbat or with any of the generic
	arrows from the Unicode Arrows block (U+2190 -- U+21FF).
	In other words, since the Zapf Dingbats refer to glyphs from
	a specific typeface, their semantic value *is* their shape.

Good Luck.

	Justifying the "Letterlike Symbols" (U+2100 -- U+214F)
is, OTOH, a piece of cake.  In a Mathematical context, one might
use both the symbol "C" (U+0043, LATIN CAPITAL LETTER C) and a
bold-faced "C" (U+2102), and have each refer to a different set
of Mathematical entities.  Mathematical typesetting is peculiar,
in that a character's rendition can carry meaning. A normal "C"
can be many things, but a bold-faced "C" is the set of complex
numbers; bold-faced "Z" is the set of integers (from the German
"Zahlen", I think). Bold-faced "B", "D", and "Y" are nothing in
particular, so far as I have ever seen.  UNICODE includes
bold-faced "C" and "Z" (U+2124), and does not include bold-faced
"B", "D", or "Y". In fact, the complete list of bold-faced
letters found in the "Letterlike Symbols" block within UNICODE
is: 

	C (U+2102) -- complex numbers
	H (U+210D) -- quaternions, a.k.a. "Hamiltonians"
	N (U+2115) -- natural numbers
	P (U+2119) -- ????
	Q (U+211A) -- rational numbers
	R (U+211D) -- real numbers
	Z (U+2124) -- integers

Unfortunately, it does not include a bold-faced "O" for the
"Octonions" or "Cayley numbers".  My point is, though, that these
letters, when rendered in bold-face, have specific meanings:  in
Mathematical contexts, they are not simply glyphic variants
yielding "typographical richness", but genuinely different
characters. 

	Sorry to go on so about this, but future typographers
need to understand this about the Mathematical characters: 
they're not just there "for pretty."  They carry definite
meanings.  It helps the author if they're available, it helps
the reader even more if they're used.  


		Rodger Hendricks (reh@pine.circa.ufl.edu)
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