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<p class="MsoPlainText">Hey, David.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">Great to hear from you. <span style="font-family:"Segoe UI Emoji",sans-serif">
😊</span> There was absolutely no disrespect intended. I assume that, throughout the timeline of feature descriptions (and the spec as a whole), people were working with good and reasonable intentions doing the best they could with available knowledge and resources.
Thanks for all you contributed in those early years, and since.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">Peter<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">-----Original Message-----<br>
From: David Lemon <typenerd@mindspring.com> <br>
Sent: Monday, September 7, 2020 11:37 PM<br>
To: Peter Constable <pgcon6@msn.com><br>
Cc: MPEG OT Spec list (mpeg-otspec@lists.aau.at) <mpeg-otspec@lists.aau.at><br>
Subject: Re: [MPEG-OTSPEC] "application interface" in feature descriptions</p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">I think I'm responsible for those redundancies. I will throw myself on the mercy of the court and just point out that I have no training whatsoever in spec writing, and at that point Adobe wasn't offering the services of anyone who did.
We were trying to standardize what sorts of things to cover in feature descriptions, and since some had unique information for processing we thought it might be best to include the "interface" section for all, even when it simply stated the obvious. In hindsight
this wasn't the brightest choice. Sorry.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">FWIW I'm delighted that there's finally some serious effort to clean up the spec.<o:p></o:p></p>
<p class="MsoPlainText">David Lemon<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">-----Original Message-----<o:p></o:p></p>
<p class="MsoPlainText">>From: Peter Constable <<a href="mailto:pgcon6@msn.com"><span style="color:windowtext;text-decoration:none">pgcon6@msn.com</span></a>><o:p></o:p></p>
<p class="MsoPlainText">>Sent: Sep 7, 2020 7:56 PM<o:p></o:p></p>
<p class="MsoPlainText">>To: Norbert Lindenberg <<a href="mailto:mpeg-otspec@lindenbergsoftware.com"><span style="color:windowtext;text-decoration:none">mpeg-otspec@lindenbergsoftware.com</span></a>><o:p></o:p></p>
<p class="MsoPlainText">>Cc: "MPEG OT Spec list (<a href="mailto:mpeg-otspec@lists.aau.at"><span style="color:windowtext;text-decoration:none">mpeg-otspec@lists.aau.at</span></a>)" <<a href="mailto:mpeg-otspec@lists.aau.at"><span style="color:windowtext;text-decoration:none">mpeg-otspec@lists.aau.at</span></a>><o:p></o:p></p>
<p class="MsoPlainText">>Subject: Re: [MPEG-OTSPEC] "application interface" in feature descriptions<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">>> The “fina” feature and its buddies as well as the “frac” feature have additional information that needs to be maintained.<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">>Yes, since writing this mail earlier today, I've been working on other revisions in various feature descriptions and noticed there are some that are not simply repeating GSUB/GPOS details.<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">>But there are a lot that are only repeating.<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">>-----Original Message-----<o:p></o:p></p>
<p class="MsoPlainText">>From: Norbert Lindenberg <<a href="mailto:mpeg-otspec@lindenbergsoftware.com"><span style="color:windowtext;text-decoration:none">mpeg-otspec@lindenbergsoftware.com</span></a>>
<o:p></o:p></p>
<p class="MsoPlainText">>Sent: Monday, September 7, 2020 10:43 PM<o:p></o:p></p>
<p class="MsoPlainText">>To: Peter Constable <<a href="mailto:pgcon6@msn.com"><span style="color:windowtext;text-decoration:none">pgcon6@msn.com</span></a>><o:p></o:p></p>
<p class="MsoPlainText">>Cc: MPEG OT Spec list (<a href="mailto:mpeg-otspec@lists.aau.at"><span style="color:windowtext;text-decoration:none">mpeg-otspec@lists.aau.at</span></a>) <<a href="mailto:mpeg-otspec@lists.aau.at"><span style="color:windowtext;text-decoration:none">mpeg-otspec@lists.aau.at</span></a>><o:p></o:p></p>
<p class="MsoPlainText">>Subject: Re: [MPEG-OTSPEC] "application interface" in feature descriptions<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">>As I pointed out in<o:p></o:p></p>
<p class="MsoPlainText">><a href="https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FMicrosoftDocs%2Ftypography-issues%2Fissues%2F290&data=02%7C01%7C%7C57927bd563714a4404b708d853c18c28%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637351438025044851&sdata=Ga8L5nQFzIuJvAjuBE0CedWXMOjDgI2fIK83HrBF3uw%3D&reserved=0"><span style="color:windowtext;text-decoration:none">https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FMicrosoftDocs%2Ftypography-issues%2Fissues%2F290&data=02%7C01%7C%7C57927bd563714a4404b708d853c18c28%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637351438025044851&sdata=Ga8L5nQFzIuJvAjuBE0CedWXMOjDgI2fIK83HrBF3uw%3D&reserved=0</span></a><o:p></o:p></p>
<p class="MsoPlainText">>talking about applications in this context is misleading. In reality, you’re talking about the interpretation of features in rendering systems.<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">>To the extent that an “application interface” section just describes how the lookups of the feature are applied, I’d agree that it can be replaced with a reference to a generic description of that process in the GSUB or GPOS documentation,
as applicable.<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">>The “fina” feature and its buddies as well as the “frac” feature have additional information that needs to be maintained. There may be others. You’ll need to read each one to decide whether there’s useful information or whether it’s
just redundant.<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">>Best regards,<o:p></o:p></p>
<p class="MsoPlainText">>Norbert<o:p></o:p></p>
<p class="MsoPlainText">>Lindenberg Software LLC<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">>> On Sep 7, 2020, at 11:16, Peter Constable <<a href="mailto:pgcon6@msn.com"><span style="color:windowtext;text-decoration:none">pgcon6@msn.com</span></a>> wrote:<o:p></o:p></p>
<p class="MsoPlainText">>> <o:p></o:p></p>
<p class="MsoPlainText">>> In feature descriptions in the OT and OFF feature registry, one of the fields of information is “Application interface”. The wording of most (all?) of these is strange because they’re worded as though a feature is a function. E.g.,
<o:p></o:p></p>
<p class="MsoPlainText">>> <o:p></o:p></p>
<p class="MsoPlainText">>> “Application interface: For GIDs found in the 'valt' coverage table, the application passes the GIDs to the table and gets back positional adjustments (YPlacement).”<o:p></o:p></p>
<p class="MsoPlainText">>> <o:p></o:p></p>
<p class="MsoPlainText">>> While it might be clear to most what is meant, strictly this is nonsense since neither Feature tables nor the associated lookup (sub)tables are functions: they’re just data.<o:p></o:p></p>
<p class="MsoPlainText">>> <o:p></o:p></p>
<p class="MsoPlainText">>> This was called out by Simon Cozens in discussion of an issue for one of the feature descriptions, but it’s a more general issue. I’ve opened an issue against the OT spec for this and have drafted revised wording for several descriptions
(for u to z) to provide a sense of what better wording might look like.<o:p></o:p></p>
<p class="MsoPlainText">>> <o:p></o:p></p>
<p class="MsoPlainText">>> Having said that, it seems to me that the Application interface information (at least, for most descriptions) is completely redundant as it simply repeats what is defined in the GPOS and GSUB chapters (how are lookup subtables used
in processing glyph sequences). So, it makes me wonder…<o:p></o:p></p>
<p class="MsoPlainText">>> <o:p></o:p></p>
<p class="MsoPlainText">>> Q: Would it be better if the Application interface portion of feature descriptions were removed?<o:p></o:p></p>
<p class="MsoPlainText">>> <o:p></o:p></p>
<p class="MsoPlainText">>> Q: Is there any feature for which there is some useful application information that isn’t a repeat of GPOS/GSUB that should be kept?<o:p></o:p></p>
<p class="MsoPlainText">>> <o:p></o:p></p>
<p class="MsoPlainText">>> <o:p></o:p></p>
<p class="MsoPlainText">>> <o:p></o:p></p>
<p class="MsoPlainText">>> Peter<o:p></o:p></p>
<p class="MsoPlainText">>> _______________________________________________<o:p></o:p></p>
<p class="MsoPlainText">>> mpeg-otspec mailing list<o:p></o:p></p>
<p class="MsoPlainText">>> <a href="mailto:mpeg-otspec@lists.aau.at"><span style="color:windowtext;text-decoration:none">mpeg-otspec@lists.aau.at</span></a><o:p></o:p></p>
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<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">>_______________________________________________<o:p></o:p></p>
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