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

Thu Jan 5 22:00:00 CET 2017

I agree. It is even more confusing when the same character is used to describe the range of negative values, as is sometimes the case for operand encoding.
What I did as part of the editorial changes when introducing the CFF2 content into the 14496-22 4th edition working draft is to use hyphen-minus for all arithmetic operations (both negation and subtraction) with no spaces, and en dash with spaces for value range, when it’s defined using both negative and positive numbers. I think that using verbal definition “X to Y” would be much less confusing, but the amount of editorial changes that would be required to make it consistent throughout the spec makes it a daunting task.

Vladimir

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, January 05, 2017 3:37 PM
To: Ken Lunde; Opstad, Dave
Cc: mpeg-OTspec at yahoogroups.com
Subject: RE: [mpeg-OTspec] OFF Font variations Working Draft for review

I agree. Having a B. Math degree, I like that notation, but it’s not going to be familiar enough to the general audience of the spec.

I’ve reviewed all the cases in which the HTML files for the OT spec have an – entity reference. In cases like head.flags or OS/2.ulUnicodeRange where a numeric range of bits is specified, there’s no ambiguity in using an en dash.

The CFF2 and CFF2 CharString specs are a little different, though, since there are sections in which ranges of byte codes are given that are interpreted as encoded numeric values, and then in the same context there are formulas for the interpretation that involve negation and subtraction operators. There are some inconsistencies, particularly use of both en dash and hyphen-minus for a negation operator. E.g., in table 3 within CFF2.htm, these strings occur:

-107 – +107
–(b0 – 251) * 256 – b1 – 108

Both use en dash for the subtraction operator, but they differ in the character used as a negation operator.

I’m inclined to use hyphen-minus for the negation operator, en dash with spaces for the subtraction operator, and list all the ranges using “to”. But I welcome input from those that are better-qualified typographers than I.

Peter

From: mpeg-OTspec at yahoogroups.com<mailto:mpeg-OTspec at yahoogroups.com> [mailto:mpeg-OTspec at yahoogroups.com] On Behalf Of Ken Lunde lunde at adobe.com<mailto:lunde at adobe.com> [mpeg-OTspec]
Sent: Thursday, January 5, 2017 12:18 PM
To: Opstad, Dave <dave.opstad at monotype.com<mailto:dave.opstad at monotype.com>>
Cc: mpeg-OTspec at yahoogroups.com<mailto:mpeg-OTspec at yahoogroups.com>
Subject: Re: [mpeg-OTspec] OFF Font variations Working Draft for review

Dave,

In the spirit of making specifications easier to read and understand, I would very strongly advise against using such notations, on the grounds that most people are not familiar with them.

Regards...

-- Ken

> On Jan 5, 2017, at 12:09 PM, 'Opstad, Dave' dave.opstad at monotype.com<mailto:dave.opstad at monotype.com> [mpeg-OTspec] <mpeg-OTspec-noreply at yahoogroups.com<mailto:mpeg-OTspec-noreply at yahoogroups.com>> wrote:
>
>
> 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 Constablepetercon at microsoft.com<mailto:Constablepetercon 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
> 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<http://www.tiro.com>
> Salish Sea, BC tiro at tiro.com<mailto:tiro at tiro.com>
>
> NOTE: In the interests of productivity, I am currently dealing with email on only two days per week, usually Monday and Thursday unless this schedule is disrupted by travel. If you need to contact me urgently, please use some other method of communication. Thank you.
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>

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