[mpeg-OTspec] Updated 4th edition working draft available for review

Peter Constable petercon at microsoft.com
Fri Mar 31 06:48:41 CEST 2017

Here is wording I have in mind for incorporating into v.next: in the "OpenType Layout Common Table Formats" chapter, in the Script List Table and Script Record section, replace the three paragraphs that follow the two bulleted items with the following:

        A ScriptList table consists of a count of the scripts represented by the glyphs in the font (ScriptCount) and
        an array of records (ScriptRecord), one for each script for which the font defines script-specific features
        (a script without script-specific features does not need a ScriptRecord). <span class="highlight">Each ScriptRecord
        consists of a ScriptTag that identifies a script, and an offset to a Script table. The ScriptRecord array is stored
        in alphabetic order of the script tags.</span>

        A Script table with the script tag 'DFLT' (default) may be used in a font to define features that are not
        script-specific. An application should use a 'DFLT' script table if there is not a script table associated
        with the specific script of the text being formatted, or if the text does not have a specific script (for
        example, it contains only symbols or punctuation). If there is a 'DFLT' script table, it must have a non-NULL
        DefaultLangSys value, which provides the offset to a default Language System table (described below). As any
        language is written using a particular script, it is normally expected that language-specific typographic
        effects will be associated with the particular script, not with the generic 'DFLT' script. For this reason,
        the LangSysCount value of a 'DFLT script table should normally be 0 (no non-default language system tables).
        A font is permitted to have a 'DFLT' script table with non-default language system tables, and an application
        may use features associated with one of these if the the 'DFLT' script table is applicable (no script table
        is present for the specific script), and if one of the particular language systems is specified. Applications
        are not required to support use of a non-default language system table that is associated with 'DFLT' script,
        however, and fonts should not depend on this configuration being supported.


From: mpeg-OTspec at yahoogroups.com [mailto:mpeg-OTspec at yahoogroups.com] On Behalf Of Peter Constable petercon at microsoft.com [mpeg-OTspec]
Sent: Thursday, March 30, 2017 4:11 PM
To: Martin Hosken <martin_hosken at sil.org>; Levantovsky, Vladimir <Vladimir.Levantovsky at monotype.com>; mpeg-OTspec at yahoogroups.com
Subject: RE: [mpeg-OTspec] Updated 4th edition working draft available for review

I've looked into Martin's request, and I think it will be OK to relax the constraint, though I think there should be some caveats/qualifications. I'll work on what I think would be appropriate wording - I'll try to do that quickly in case Vlad is able to incorporate something into docs for the upcoming MPEG meeting.


-----Original Message-----
From: Martin Hosken [mailto:martin_hosken at sil.org]
Sent: Tuesday, March 21, 2017 3:00 AM
To: 'Levantovsky, Vladimir' vladimir.levantovsky at monotype.com<mailto:vladimir.levantovsky at monotype.com> [mpeg-OTspec] <mpeg-OTspec-noreply at yahoogroups.com<mailto:mpeg-OTspec-noreply at yahoogroups.com>>
Cc: mpeg-OTspec at yahoogroups.com<mailto:mpeg-OTspec at yahoogroups.com>; darnold at adobe.com<mailto:darnold at adobe.com>; rroberts at adobe.com<mailto:rroberts at adobe.com>; Ken Lunde (lunde at adobe.com<mailto:lunde at adobe.com>) <lunde at adobe.com<mailto:lunde at adobe.com>>; Peter Constable <petercon at microsoft.com<mailto:petercon at microsoft.com>>
Subject: Re: [mpeg-OTspec] Updated 4th edition working draft available for review

Dear Vladimir,

> This is just a friendly reminder that we have one week left to discuss the changes in the 4th edition Working Draft of the OFF standard. Your comments on both previously introduced and newly proposed changes would be much appreciated. We've had significant changes made in the description of the CFF2 table and CFF2 CharString format - I'd like to ask for your time to review and comment on these portions of the document.

As mentioned a few times now:

> I would like to return to a discussion thread that got dropped a while back and that is I would like to remove the following paragraph from chapter2:
> "If a Script table with the script tag 'DFLT' (default) is present in the ScriptList table, it must have a non-NULL DefaultLangSys and LangSysCount must be equal to 0. The 'DFLT' Script table should be used if there is not an explicit entry for the script being formatted."


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