[mpeg-OTspec] OFF Font variations Working Draft for review

[Opstad, Dave]

Mathematics already provides an alternative and unambiguous notation for ranges: [a, b] for closed (i.e. includes a and b), and (a, b) for open (does not include a or b). These may be mixed as well: [0, 1000) for instance specifies a value from 0 through 999.

Maybe it makes sense to adopt something like this?

Cheers,
Dave

From: <mpeg-OTspec at yahoogroups.com<mailto:mpeg-OTspec at yahoogroups.com>> on behalf of "Peter Constable petercon at microsoft.com<mailto:petercon at microsoft.com> [mpeg-OTspec]" <mpeg-OTspec-noreply at yahoogroups.com<mailto:mpeg-OTspec-noreply at yahoogroups.com>>
Reply-To: Peter Constable <petercon at microsoft.com<mailto:petercon at microsoft.com>>
Date: Thursday, January 5, 2017 at 11:37
To: John Hudson <john at tiro.ca<mailto:john at tiro.ca>>, Indra Kupferschmid <kupfers at gmail.com<mailto:kupfers at gmail.com>>, "mpeg-OTspec at yahoogroups.com<mailto:mpeg-OTspec at yahoogroups.com>" <mpeg-OTspec at yahoogroups.com<mailto:mpeg-OTspec at yahoogroups.com>>
Subject: RE: [mpeg-OTspec] OFF Font variations Working Draft for review



I looked a bit more into what's actually being done in the OT spec. Interestingly, I discovered that the CFF2 and CFF2 CharString chapters, which Adobe primarily authored, have many instances of en dash surrounded by spaces to indicate a numeric range. These chapters also have en dashes used as a negation sign (without space between the dash and the number), and as a minus operator — sometimes with and sometimes without spaces.

In a technical spec like this, the biggest pitfall to avoid would be confusion about numeric range versus negation or subtraction. In some contexts, it may reasonably clear, but using words "from... to..." for numeric ranges, as in OT's wording for OS/2.usWeightClass, eliminates ambiguity. Words may not be desirable in every context, though. Perhaps that's why the CFF2 authors put spaces before/after en dash when indicating a numeric range.


Peter

-----Original Message-----
From: John Hudson [mailto:john at tiro.ca]
Sent: Thursday, January 5, 2017 10:24 AM
To: Indra Kupferschmid <kupfers at gmail.com<mailto:kupfers at gmail.com>>; Peter Constable <petercon at microsoft.com<mailto:petercon at microsoft.com>>; mpeg-OTspec at yahoogroups.com<mailto:mpeg-OTspec at yahoogroups.com>
Subject: Re: [mpeg-OTspec] OFF Font variations Working Draft for review

On 05/01/17 09:54, Indra Kupferschmid kupfers at gmail.com<mailto:kupfers at gmail.com> [mpeg-OTspec] wrote:

> Oh disregard, I did not read well enough. I thought you were talking
> about dashes – like this. Ranges, list 0–100 are set with en-dash
> without space.

Yes. The distinction is between whether the dash is used to separate items or to link them as in a number range.

JH


--

John Hudson
Tiro Typeworks Ltd www.tiro.com
Salish Sea, BC tiro at tiro.com<mailto:tiro at tiro.com>

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