From: Frank da Cruz (fdc@columbia.edu)
Date: Thu Mar 13 2003 - 11:53:01 EST
> I've got a few questions about the use of geometric shapes, like
> squares and such.
> Some of these look very similar to one another, and I don't know
> which ones to use in which circumstances!
> Are their any guidelines on their use?
> Just as an example, let's look at the squares. These come in four
> sizes: small, medium, medium small and (not specified). So my
> question is, as a writer: which one of these should I use when
> exactly? And as a font designer: what should they look like? Is a
> medium square (U+25FB) bigger or smaller than a square (U+25A1)? Are
> there any guidelines on how they should be positioned vertically,
> relative to normal text? Etc.
> The same goes for other shapes, of course. For instance, what
> criteria exist for, when creating a text, choosing between U+25B6,
> U+25B8 and U+25BA?
> Are there URLs available shich discuss these issues?
>
Block characters, as well as box- and line-drawing characters in general,
are mainly inherited from character sets in which they were included for
the purpose of character-cell graphics (e.g. on terminal screens,
text-mode DOS applications, etc), and their use makes sense only in a
monospace font.
To my knowledge, the semantics of most of these characters is not described
anywhere, which leaves them open to misinterpretation, especially by font
designers who are not aware (e.g.) that such-and-such a line must extend to
the edges of cell, so it can join up with copies of itself in adjacent cells
to form an unbroken line. Or that the two lines of "lower left box corner"
must touch and bisect the top and right edges of the cell. And so on.
In part this is explained by the fact that the original character sets from
which these characters were inherited were themselves documented only by
tables showing the glyphs, never by a description of how the glyphs were to
be used, or line up. Only experimentation with an actual terminal
(e.g. VT220) or PC code page (e.g. CP437) can reveal such things.
The same concerns apply to some of the math characters -- integral and
summation sign pieces, etc, but then the character's purpose more obvious,
if not from its appearance, then from its name.
For a bit more on this topic, see the "Supplemental Terminal Graphics for
Unicode" writeup:
ftp://kermit.columbia.edu/kermit/ucsterminal/ucsterminal.txt
for Unicode 3.2:
http://www.unicode.org/reports/tr28/index.html
- Frank
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