Re: Controls, gliphs, flies, lemonade

From: John H. Jenkins <>
Date: Tue, 13 Sep 2011 11:34:20 -0600

QSJN 4 UKR 於 2011年9月12日 下午9:06 寫道:

> I know it is sacred cow, but let me just ask, how do you people think.
> Is it good or bad that the codepoint means all about character: what,
> where, how... (see theme)? Maybe have we separate graph & control
> codes - wellnt have many problems, from banal ltr (( rtl instead ltr
> (rtl) to placing one tilde above 3, 4, anymore letters, or egyptian
> hierogliphs in rows'n'cols. Conceptually, I mean! Each letter in text
> is at least two codepoints ("what" and "where") in file. Is it stupid?
> Trying to render the text we anyway must generate this data.

It's not really a sacred cow per se, but it is a fundamental architectural decision which would be pretty much impossible to revisit now.

Almost all writing is done using a small set of script-specific rules which are pretty straightforward. English, for example, is laid out in horizontal lines running left-to-right and arranged top-to-bottom of the writing surface. East Asian languages were traditionally laid out in vertical lines running from top-to-bottom and arranged right-to-left on the writing surface.

Because some scripts are right-to-left and ltr and rtl text can be freely intermingled on a single line, Unicode provides plain-text directionality controls. The preference, however, is to use higher-level protocols where possible.

As for the scripts which are inherently two-dimensional (using hieroglyphics, mathematics, and music), it's almost impossible to provide "plain text" support for them. There is too much dependence on additional information such as the specifics of font and point size. Because of this, the UTC decided long ago that layout for such scripts absolutely must be done using a higher-level protocol to handle all the details.

There are occasionally suggestions that positioning controls be added to plain text in Unicode, but so far the UTC has felt that the benefits are too marginal to overcome its reasons for having left them out in the first place.

Hoani H. Tinikini
John H. Jenkins
Received on Tue Sep 13 2011 - 13:24:01 CDT

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