<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>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'.</div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">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.</div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">JH</div><div id="AppleMailSignature"><br><br>Sent from my iPad</div><div><br>On Mar 31, 2017, at 5:34 PM, Peter Constable <<a href="mailto:petercon@microsoft.com">petercon@microsoft.com</a>> wrote:<br><br></div><blockquote type="cite"><div>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">John:<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">Can you clarify for me what specifically about which part of the wording concerns you.<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">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:<o:p></o:p></span></p>
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<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">”<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">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.<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">Is this concern with this?<o:p></o:p></span></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">“</span><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><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">”<o:p></o:p></span></p>
<p class="MsoNormal"><a name="_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">If so, I could work on that.<o:p></o:p></span></a></p>
<p class="MsoNormal"><span style="mso-bookmark:_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Peter<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></span></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>]
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<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<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">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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Sent from my iPad<o:p></o:p></p>
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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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