Re: IDS rendering and IDS analysis (was RE: Problems/Issues with CJK

From: John Jenkins (
Date: Tue Apr 11 2000 - 00:44:58 EDT

on 4/10/00 6:12 AM, at

> However, the 3.0 book and other sources now timidly mention "IDS rendering".
> This means that an Unicode display engine has the faculty (but *not* the
> obligation!) to generate a glyph on-the-fly, and display it in place of the
> IDS itself.

No current Unicode display engine has the faculty to generate a glyph
on-the-fly. Some have the ability to substitute single glyphs for an entire
IDS if such is known in advance by a font designer.

> This naturally leads to Jon's thought: what if IDS, or a similar mechanism,
> is generalized to all CJK characters? Wouldn't it be possible to encode any
> CJK text with only a handful of combining logical units? Or, alternatively,
> wouldn't it be possible to design "light" CJK fonts, containing only glyphs
> for the basic graphic units?

Theoretically, this is true. In practice, it is not. There are enormous
problems of graphic variation, ambiguity in the breakdown, and breakdown
into non meaningful pieces. Think of trying to describe Latin text using a
handful of curves and straight lines with appropriate connectors.

John H. Jenkins

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