Re: WOFF 2.0: Known Table Tags Proposal

OK, great, thank you Behdad.  Adding Raph to sanity check.

Here is the updated (and streamlined) proposal then:

See the "Proposals (fewer tables)" tab:
https://docs.google.com/a/google.com/spreadsheets/d/111MT0l7LOVqotAnMXD4PMOm36jTPSznUigJPfxUYY_0/edit#gid=0

In summary, the proposed changes to the draft specification (
http://dev.w3.org/webfonts/WOFF2/spec/) are:

o  The known table tags from the draft specification [ 0 for 'cmap' through
28 for 'GSUB' ] are preserved as is
o  The earlier "reserved - invalid" bits (29, 30) are removed (the bits
have been reassigned)
o  The "arbitrary tag follows" moves from 31 to 48 (do we still need this?)
o  The new assignments start at 29 for 'EBSC' and run through 47 for 'Sill'
(see below)

Proposed new assignments:

29 EBSC
30 JSTF
31 DSIG
32 CBDT
33 CBLC
34 sbix
35 COLR
36 CPAL
37 "SVG "
38 feat
39 just
40 mort
41 morx
42 MATH
43 Silf
44 Glat
45 Gloc
46 Feat
47 Sill

LGTM?

On Mon, Apr 14, 2014 at 4:10 PM, Behdad Esfahbod <behdad@google.com> wrote:

> SGTM.  And again, I don't think this is worth any more of your (or the
> working group's) time.
>
>
> On Mon, Apr 14, 2014 at 3:54 PM, David Kuettel <kuettel@google.com> wrote:
>
>> On Mon, Apr 14, 2014 at 6:37 AM, Levantovsky, Vladimir <
>> Vladimir.Levantovsky@monotype.com> wrote:
>>
>>>  I agree, for WOFF 2.0 encoding we should compile a list of popular /
>>> frequently used tables, and any one-of-a-kind table that is rarely seen can
>>> simply be treated as an arbitrary tag. As far as table tags in general are
>>> concerned, the SFNT /TrueType / OpenType common structures presume that all
>>> original TrueType tags are spelled in lowercase letters, and all other tags
>>> should be all caps only. The mix of caps / lowercase characters in the same
>>> tag is not permitted.
>>>
>>
>> Thank you Vlad, Behdad, John and Sergey.
>>
>> Exploring this ("popular / frequently used tables") further, would we be
>> open to omitting the older unused Apple/TrueType tables?
>>
>> For example, with the corpus of fonts that I tested with, I did not find
>> any fonts using the acnt, avar, bdat, bloc, bsln, cfar, fdsc, fmtx, fvar,
>> gvar, hsty, lcar, opbd, prop, track or Zapf tables.  Rather, the few that
>> were used include: feat, just, mort, motx.  Were we open to exploring this,
>> we would likely want to check a larger collection of fonts to confirm of
>> course.
>>
>> To summarize (and capture the most recent proposals), shall we add tags
>> for the following known tables:
>>
>> [ See column B, with the additional tables highlighted in green ]
>>
>> https://docs.google.com/a/google.com/spreadsheets/d/111MT0l7LOVqotAnMXD4PMOm36jTPSznUigJPfxUYY_0/edit#gid=0
>>
>> (1) OpenType tables that were missed earlier: EBSC, JSTF, DSIG
>> (2) Color font proposals: CBDT, CBLC, sbix, COLR, CPAL, "SVG "
>> (3) Apple/TrueType tables (which are still used*): feat, just, mort, morx
>> (4) Microsoft MATH table: MATH
>> (5) SIL Graphite (non-standardized) tables: Silf, Glat, Gloc, Feat, Sill
>>
>> (*) Assumes we are open to dropping Apple/TrueType tables that are no
>> longer used (see above).
>>
>>>
>>>
>>> Thank you,
>>>
>>> Vlad
>>>
>>>
>>>
>>>
>>>
>>> *From:* Behdad Esfahbod [mailto:behdad@google.com]
>>> *Sent:* Friday, April 11, 2014 6:57 PM
>>> *To:* David Kuettel
>>> *Cc:* public-webfonts-wg@w3.org
>>> *Subject:* Re: WOFF 2.0: Known Table Tags Proposal
>>>
>>>
>>>
>>> At the end of the day, this doesn't matter much, we are talking saving,
>>> say, 20 bytes, for a rare font.  I think you should just fix a set and move
>>> on.
>>>
>>>
>>>
>>> On Fri, Apr 11, 2014 at 3:51 PM, David Kuettel <kuettel@google.com>
>>> wrote:
>>>
>>> On Fri, Apr 11, 2014 at 2:41 PM, Behdad Esfahbod <behdad@google.com>
>>> wrote:
>>>
>>> Thanks David.  Your code may be buggy with tags that have space in them.
>>>  It doesn't make sense that you didn't find any "cvt " or "CFF ".  Other
>>> than that, I suggest dropping EPAR as well as anything that shouldn't be in
>>> a final shipped product (VTT, etc).
>>>
>>>
>>>
>>> Great points Behdad, I should have elaborated in my earlier emails.
>>>
>>>
>>>
>>> The tool that I used was 'showttf' on Linux, which did segfault on some
>>> of the files.  A better tool would have been fonttools, esp. due to the
>>> worldclass support from you. :)
>>>
>>>
>>>
>>> The collection of fonts (while good sized) did not contain
>>> PostScript/CFF fonts.  I need a bigger test set.
>>>
>>>
>>>
>>> Really, lets just keep this to the union of OpenType spec, Apple
>>> TrueType, Graphite, and color fonts.
>>>
>>>
>>>
>>> Regarding the Apple TrueType font tables, given that so few are likely
>>> still in use today, would it make since to whittle down the list a bit?  Or
>>> perhaps again, my test collection was too limited.
>>>
>>>
>>>
>>> Cheers,
>>>
>>> behdad
>>>
>>>
>>>
>>> On Fri, Apr 11, 2014 at 2:05 PM, David Kuettel <kuettel@google.com>
>>> wrote:
>>>
>>> To sanity check the initial list, I dumped the tables over a moderate
>>> sized collection of fonts, and then color coded the entries in the
>>> spreadsheet to reflect real-world usage (for this collection).
>>>
>>>
>>>
>>>
>>> https://docs.google.com/a/google.com/spreadsheets/d/111MT0l7LOVqotAnMXD4PMOm36jTPSznUigJPfxUYY_0/edit#gid=0
>>>
>>>
>>>
>>> The color coding ranges from dark green, to represent the most commonly
>>> used tables (e.g. name, glyph), to light green, to represent the least
>>> commonly used tables (e.g. JSTF, mort, Silf, etc).
>>>
>>>
>>>
>>> The red entries represent tables that were not found with this
>>> collection (e.g. acnt, fmtx, TeX, etc).
>>>
>>>
>>>
>>> The white (no color) entries represent tables that likely would have
>>> been present in a larger collection (e.g. CFF, cvt, sbix, COLR, etc).
>>>
>>>
>>>
>>>
>>>
>>> Interestingly enough, the more tables that I look for, the more I find.
>>>  For example, FontLab's Glossary page documents a ton of optional font
>>> tables: http://blog.fontlab.com/info/  e.g. TSI1..TSIV and many more.
>>>
>>>
>>>
>>> Thus, I am wondering if we should revisit the goal of trying to capture
>>> all known / used table tags.  Perhaps, esp. in light of this data, it would
>>> be better to just capture the most commonly used tables today, while
>>> ensuring that the rarely used ones would simply be passed through the WOFF
>>> 2.0 encode/decode process...
>>>
>>>
>>>
>>> Thoughts?
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>