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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">OK, here my proposed revised wording, taking Johns comment into consideration:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:10.0pt;font-family:"Georgia",serif">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 style="color:green;background:#FFFF9F">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>
<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:10.0pt;font-family:"Georgia",serif"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in;background:#FFFF9F"><span style="font-size:10.0pt;font-family:"Georgia",serif;color:green">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).
<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:10.0pt;font-family:"Georgia",serif"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:1.0in;background:#FFFF9F"><i><span style="font-size:10.0pt;font-family:"Georgia",serif;color:green">Note:</span></i><span style="font-size:10.0pt;font-family:"Georgia",serif;color:green"> If symbols or punctuation have
a Unicode script property “Common” but are used together with characters of a specific script, features that apply to those symbol or punctuation characters should not necessarily be organized under the 'DFLT' script, but can be organized under the specific
script. Applications may process script-neutral characters together with immediately-preceding or following script-specific characters for better processing efficiency. In that case, an application would look for features that operate on the neutral characters
by using the Script table for the specific script. The ‘DFLT’ script would still be used if the text contained only the neutral characters, however.<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:10.0pt;font-family:"Georgia",serif"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in;background:#FFFF9F"><span style="font-size:10.0pt;font-family:"Georgia",serif;color:green">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 languages are written using particular scripts, 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). However, 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, or there is no specific script in the text context), and if one of the particular language systems is specified. Applications should support use of a non-default
language system table that is associated with 'DFLT' script, though some applications might not do so.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Let me know if that addresses your concerns adequately.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Peter<o:p></o:p></span></p>
<p class="MsoNormal"><a name="_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></a></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> John Hudson [mailto:john@tiro.ca]
<br>
<b>Sent:</b> Monday, April 3, 2017 1:49 AM<br>
<b>To:</b> Peter Constable <petercon@microsoft.com><br>
<b>Cc:</b> Martin Hosken <martin_hosken@sil.org>; Levantovsky, Vladimir <Vladimir.Levantovsky@monotype.com>; mpeg-OTspec@yahoogroups.com<br>
<b>Subject:</b> Re: [mpeg-OTspec] Updated 4th edition working draft available for review<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">My concern is that the proposed wording relaxes the requirement that the language system count be zero, but then states that implementations are not required to do anything with any language systems mapped to the DFLT script. So it's basically
saying 'Yes, you can have an unreliable mechanism'.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I would rather the wording say something to the effect that language systems mapped to the DFLT script tag should be treated the same as language systems mapped to any other script tag, rather than suggesting, as the proposed wording does,
that the DFLT script remains a special case with regard to language systems. Implementations may still fail to support language system tags in various ways — as they do already —, but should do so consistently regardless of whether the script tag is specific
or DFLT.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">JH<o:p></o:p></p>
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<p class="MsoNormal"><br>
<br>
Sent from my iPad<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><br>
On Mar 31, 2017, at 5:34 PM, Peter Constable <<a href="mailto:petercon@microsoft.com">petercon@microsoft.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">John:</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Can you clarify for me what specifically about which part of the wording concerns you.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">I think I’ve stayed consistent with what the spec was already saying about DFLT script tag in general, and only stated it (I think) more clearly:</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">“</span><span style="font-family:"Georgia",serif">The 'DFLT' Script table should be used if there is not an explicit entry for the script being formatted.</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">”</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">The key change has been to relax the constraint that LangSysCount “must be equal to 0”. “A font is permitted…” is implied if that constraint has been relaxed.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Is this concern with this?</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">“An application should use a 'DFLT' script table … if the text does not have a specific script (for example, it contains
only symbols or punctuation).”</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">If so, I could work on that.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Peter</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> </span><o:p></o:p></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> John Hudson [<a href="mailto:john@tiro.ca">mailto:john@tiro.ca</a>]
<br>
<b>Sent:</b> Friday, March 31, 2017 6:56 AM<br>
<b>To:</b> Peter Constable <<a href="mailto:petercon@microsoft.com">petercon@microsoft.com</a>><br>
<b>Cc:</b> Martin Hosken <<a href="mailto:martin_hosken@sil.org">martin_hosken@sil.org</a>>; Levantovsky, Vladimir <<a href="mailto:Vladimir.Levantovsky@monotype.com">Vladimir.Levantovsky@monotype.com</a>>;
<a href="mailto:mpeg-OTspec@yahoogroups.com">mpeg-OTspec@yahoogroups.com</a><br>
<b>Subject:</b> Re: [mpeg-OTspec] Updated 4th edition working draft available for review</span><o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">Peter, I'm a bit concerned that this wording makes some assumptions about how implementations use the DFLT script tag, without those implementations being specified anywhere. [Well, nothing new in that: this is true of OpenType Layout in
general.] So, for example, I've seen DFLT used by Adobe to process script=common characters such as the Indic danda and double danda from the Unicode Devanagari block, which are also used by other Indian scripts. If one wanted to make a pan-Indic font with
script-specific forms of danda, the only way to do so within that implementation would be via language system under the DFLT script tag. Of course, the case can be made that such an implementation is wrong, but sans an implementation spec, I wonder about the
wisdom of specifying constraints in the format spec.<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">JH<o:p></o:p></p>
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<p class="MsoNormal"><br>
<br>
Sent from my iPad<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><br>
On Mar 31, 2017, at 5:48 AM, Peter Constable <a href="mailto:petercon@microsoft.com">
petercon@microsoft.com</a> [mpeg-OTspec] <<a href="mailto:mpeg-OTspec-noreply@yahoogroups.com">mpeg-OTspec-noreply@yahoogroups.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">A font is permitted to have a 'DFLT' script table with non-default language system tables, and an application
</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> may use features associated with one of these if the the 'DFLT' script table is applicable (no script table
</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> is present for the specific script), and if one of the particular language systems is specified. Applications
</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> are not required to support use of a non-default language system table that is associated with 'DFLT' script,
</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> however, and fonts should not depend on this configuration being supported.</span><o:p></o:p></p>
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