From: John H. Jenkins (jenkins@apple.com)
Date: Mon Oct 29 2007 - 19:49:58 CST
On Oct 29, 2007, at 6:28 PM, Andrew West wrote:
> On 29/10/2007, Peter Constable <petercon@microsoft.com> wrote:
>>
>> I guess I assumed that that was never intended to provide a
>> substitute for encoding the characters needed for Zhuang text -- it
>> would be a terrible way to represent Zhuang text, though I suppose
>> you can argue (as you have done) that it's valid.
>
> I'm sure that John has never suggested that IDS sequences should be a
> substitute for encoding, merely that given what the Unicode Standard
> currently says, it would be a feasible interim solution.
>
TUS is most emphatic on this point: An IDS is *not* the same thing as
encoding. It should be considered a better-than-nothing stop-gap
until something appropriate comes along (either an encoded character
or a registered variation sequence). I suppose that a text in say
Zhuang could use a custom font to hide the fact that most of it
consists of IDSs, but in such a case Unicode explicitly warns that no
operation other than display-related ones will likely work. Using an
IDS in running text is a hack.
> The question is just what exactly the intent of that paragraph in the
> Unicode Standard was. It sure sounds to me as if it is suggesting (and
> Unicode is sanctioning) a mechanism for component based represention
> of unencoded ideographs -- if the character was already encoded why
> would you want the rendering system to render an IDS as a single glyph
> and treat it as a single unit for editing purposes?
>
The intent is to allow systems to represent IDSs using single glyphs,
if they can and choose to do so, either through on-the-fly composition
(which will almost certainly be pretty ugly) or through the ligature
mechanisms available in smart fonts. The latter is more likely. In
this case someone with a need to represent a particular unencoded
character (or a set of such) could use a custom font to, at least,
make their text look decent.
> I guess it must have been written at a time when people didn't worry
> so much about security and spoofing issues. I would suggest that the
> UTC should consider removing the offending paragraph at the earliest
> opportunity, and replace it with a statement that IDS sequences are
> intended to be rendered as a visible sequence of IDC characters and
> ideographic components, and not composed into a single glyph. But then
> maybe it is too late for that now ?
>
> Andrew
>
No, go ahead and file a defect report. I doubt this would change
because I don't think the problem of spoofing is really serious for
IDSs. For one thing, for spoofing to work, you'd have to have a
system which can create decent-looking glyphs on-the-fly from IDSs,
and they're just too coarse to make that likely. For another, given
the low-utility of IDSs you simply have to state that a string
containing them isn't valid for whatever purpose. But I'm not going
to second-guess the UTC and they may think it's a serious enough
problem to take action.
=====
John H. Jenkins
jenkins@apple.com
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