"Steven T. Hatton"
Is ∑ the same as Σ? I used `ucm` to pick these characters out. This is an unusably slow process for any kind of work which involves extensive use of characters not available in the current key mapping.
Probably you only need a rather small subset of Unicode frequently. Put the characters you need often into a file, then display that file (e.g. with 'less' in a UTF-8 capable terminal) and cut & paste from there. That's faster than 'ucm' for that purpose, because you have all your frequently used characters close together.
The first '∑' is from 'U+2200' and the second 'Σ' is from U+0300. These appear identical on my SuSE 8.0 box in kmail.
Depends on the font you have setup in KMail. When using the GNU Unicode font for example, there is a small but visible difference between the glyphs for these two characters. In the efont-unicode fonts and Markus Kuhns 18 pixel unicode font (which comes with XFree86) the difference is obvious.
I copied these from kmail to and Emacs buffer and found the first of these characters is not rendered, and the second is rendered as expected.
Both XEmacs and Emacs display both characters correctly for me. Even when I don't load my ~/.emacs and use the system default ('xemacs -q' or 'emacs -q').
Hexlifying the buffer holding `∑ Σ' resulted in the following character codes: e288 9120 cea3. This could be anoying when it comes to human to human comunication.
Yes, of course the two characters are different.
It is potentially devistating when it comes to human to computer communication. For example, imagine a database of words from different languages and data entered by different users who don't fully understand the idosynchracies of UTF encoding.
You must understand which character they want to input and use the correct one: Character `∑' UNIDATA information. --------------------------------- This is converted to U+2211 under the current environment. name N-ARY SUMMATION category (symbol math) combining-class 0 => Spacing bidirectional-category ON => Other Neutrals mirrored mirrored titlecase-mapping -1 Character `Σ' UNIDATA information. --------------------------------- This is converted to U+03A3 under the current environment. name GREEK CAPITAL LETTER SIGMA category (letter uppercase) combining-class 0 => Spacing bidirectional-category L => Left-to-Right mirrored not-mirrored lowercase-mapping -1 titlecase-mapping -1 You see, one is a mathematical symbol, the other is a Greek character. Just use the correct one. That's the same as with 'O' and '0'. They may look similar in some fonts, that doesn't mean you are allowed to mix them up. That can't be helped.
To the users, everything may appear correct, but what were intended to be equivalent strings entered by different users may actually be two distinct representations of the same human readable representation.
Looks like you have not yet discovered combining characters:
For example, you can write a ö in different ways as well:
U+00F6 LATIN SMALL LETTER O WITH DIAERESIS
or
U+0308 COMBINING DIAERESIS
followed by
U+006F LATIN SMALL LETTER O
Try to paste those characters for example from 'ucm' into an xterm in
UTF-8 mode. You see that the result looks identical in both cases.
Nevertheless the UTF-8 sequence in the command line in the xterm is
different.
--
Mike Fabian