From: Jukka K. Korpela (jkorpela@cs.tut.fi)
Date: Sat Aug 27 2005 - 08:57:06 CDT
On Fri, 26 Aug 2005, Guy Steele wrote:
> My son asks: does Unicode have the set of symbols usually used
> to label tape transport controls on a tape deck or VCR?
I don't think there is. Generally, Unicode contains characters used in
text, not graphic symbols in general. Although the symbols you mention
could conceivably appear in texts like instruction manuals
(e.g., "then press the ... key", where "..." is an image of a key
or a button), the same applies to virtually all small graphic symbols:
they can be embedded into text as images.
There are some Unicode characters that seem to contradict what I just
wrote, but they might have been included due to their presence in other
character codes or some special reasons. Computer keyboard symbols seem to
have made their way to Unicode relatively easily, perhaps due to their
assumed need in written instructions.
To me, it would sound natural to keep graphic symbols outside Unicode (and
not treat them as characters) as long as a symbol is essentially iconic,
an image that imitates another image (such as something engraved into a
key). The imitated image may have a symbolic meaning (e.g., it could stand
for "pause" in a key that makes something pause), but this does not make
it a _character_. If it is used in texts _only_ to stand for the imitated
image, it's still essentially an image.
Things would change if people started using such a symbol in their texts
to mean "pause" in general, effectively turning it into an ideograph.
> I am speaking
> especially of the double vertical rectangle used for "pause".
It might be added some day to Unicode, but I doubt it. What benefits would
it produce? You could use it in texts, assuming you have a font that
contains it, so you could write some things in some instructions using
plain text, instead of embedding an image. But would you do so? After all,
its shape would have to be generic. When writing a manual for a particular
device, it would be better to use the specific shapes (and perhaps colors)
that appear in it. Computer keyboard symbols are a somewhat different
issue, since people may wish to use generic symbols when writing e.g.
a manual for software that may be used with different keyboards.
> I do see that Unicode already has the related U+23CF EJECT SYMBOL
> consisting of a solid triangle above a horizontal bar.
Indeed, and it is described under the heading "Keyboard and UI symbols"
and with the note "UI symbol to eject media". Its presence in Unicode
puzzles me, but it might relate to its use on computers. After all,
"UI", or "user interface", is computerese jargon.
> I checked the
> Unicode 4.1 database but the only occurrence of the word "pause" was
> in the comment for U+2389 CIRCLED HORIZONTAL BAR WITH NOTCH,
Yes. It's under the heading "Keyboard symbols from ISO 9995-7", so it's a
standardized symbol for a computer keyboard key. I wouldn't use it for
anything else.
-- Jukka "Yucca" Korpela, http://www.cs.tut.fi/~jkorpela/
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