Wireshark-dev: Re: [Wireshark-dev] UTF8 vs. locale in error messages (bug 5715)
From: Guy Harris <[email protected]>
Date: Tue, 28 Jun 2011 10:54:04 -0700
On Jun 28, 2011, at 10:43 AM, Guy Harris wrote:

> On Jun 28, 2011, at 10:27 AM, Guy Harris wrote:
> 
>> 	when putting them into a textual representation of the protocol tree or into columns or something else to be shown to humans, map them to UTF-8, with anything that can't be mapped to UTF-8 - including, if the encoding is putatively UTF-8, octet sequences that aren't valid UTF-8 sequences - shown as the Unicode replacement character U+FFFD;
> 
> ...and, for "for display" conversions, we might want to convert control characters to "Control Pictures" symbols (0x0000 to 0x001F convert to 0x2400 to 0x241f: ␀, ␁, etc. through ␟; 0x007F converts to 0x2421, i.e. ␡ - in the font in which this message is being displayed to me, those have the control character abbreviations displayed in really really small letters, diagonally from upper left to lower right; unfortunately, I see nothing for C1 control characters).

	http://en.wikipedia.org/wiki/Template:Unicode_chart_Control_Pictures

That claims that this is "as of Unicode 6.0", so, if true, either they have a different name for control pictures for C1 control characters or there aren't any.  (I have no idea what those other symbols are doing in there.)

U+FFFD is often shown as a white question mark inside a black diamond:

	http://en.wikipedia.org/wiki/Specials_(Unicode_block)

Oh, and if we're going to be extremely completist, there are the EBCDIC control characters, for which there are not always control pictures; see table 5.1:

	ftp://kermit.columbia.edu/kermit/ucsterminal/control.txt

This was from 1998.  I don't know whether any of the proposals were accepted.