RE: Language Tagging And Unicode

From: Chris Pratley (
Date: Thu Jan 20 2000 - 03:10:55 EST

Peter mentions that Word uses language information only for selecting
proofing tools, but that is not all. Word uses language for many things:
Determining date format
Determining sort order
Controlling line breaking, word breaking (for scripts that need it)
Determining many default properties

Once the necessary infrastructure (fonts, UniScribe support) is available in
at least a prototype testable form, and if I am still running things :),
you'll probably see Word start displaying language-appropriate glyphs from
fonts if they exist. From the application perspective all we need is to be
able to add a language parameter to our text rendering, and the OS should
take care of it (UniScribe is part of Windows). These things take time. I
suspect that given the standard priorities, the languages that we see this
first will be CJK. Once the infrastructure is there, third parties could
create fonts with the necessary glyph tables for languages we didn't do

Chris Pratley
Group Program Manager
Microsoft Word

-----Original Message-----
From: Peter Constable []
Sent: Wednesday, January 19, 2000 1:17 PM
To: Unicode List
Subject: Re: Language Tagging And Unicode

>Does this mean that Windows' OpenType layout services does
       support language system (even if MS are not currently making
       use of this in Office etc. applications)?


>The OpenType spec says e.g. for GSUB (glyph substitution)

>1 Locate the current script in the GSUB ScriptList table.
>2 If the language system is known, search the script for the
          correct LangSys table; otherwise, use the script's default
          language system (DefaultLangSys table).
>3 The LangSys table provides index numbers into the GSUB
          FeatureList table to access a required feature and a number
          of additional features.

>Do MS applications that use OT currently bypass (2) and just
       go straight to the default language system for any given

       My understanding is that Uniscribe *currently* does this (but I
       expect that will change).

>(Text in word Word at least has a language attribute so
       presumably that application "knows" the language system.)

       Currently, Word only uses this for selecting proofing tools.

>I've been trying to build OT fonts based on the assumption
       that applications will use the LangSys table. Am I wasting my

       No, I pray not! I doubt you're alone on this.


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