New work on 3rd edition of the OFF (AHG kick-off)

[Michelle Perham]

Vlad, thank you for all your hard work.  Microsoft would like to voice support for the new feature proposed by John Hudson, "Required Contextual Alternates". (http://tech.groups.yahoo.com/group/mpeg-OTspec/message/411)

We've spoken with John offline and drafted a feature description:

Tag: 'rclt'

Friendly name: Required Contextual Alternates

Registered by: Microsoft / Tiro Typeworks

Function: In specified situations, replaces default glyphs with alternate forms which provide for better joining behavior or other glyph relationships. Especially important in 'script' typefaces which are designed to have some or all of their glyphs join, but applicable also to e.g. variants to improve spacing. This feature is similar to 'calt', but with the difference that it should not be possible to turn off 'rclt' substitutions: they are considered essential to correct layout of the font.

Example: In an Arabic calligraphic font the 'rclt' feature is used to contextually substitute variant forms of letters sin and yeh providing for a correct join between these two letters that differs from the default join of either to other letters.

Recommended implementation: The rclt table specifies the context in which each substitution occurs, and maps one or more default glyphs to replacement glyphs (GSUB lookup type 6).

Application interface: The application passes sequences of GIDs to the feature table, and gets back new GIDs. Note that full sequences must be passed.

UI suggestion: This feature should be active by default. It is recommended that this feature not be turned off, to avoid breaking obligatory shaping.

Script/language sensitivity: May apply to any script, but is especially important for many styles of Arabic.

Feature interaction: This feature may be used in combination with other substitution (GSUB) features, whose results it may override. For complex scripts, lookups for this feature should be ordered and processed after basic script and language shaping features.


John has also created an illustration which I'll upload to the Yahoo Group site.

Thank you,
Michelle

From: mpeg-OTspec at yahoogroups.com [mailto:mpeg-OTspec at yahoogroups.com] On Behalf Of Levantovsky, Vladimir
Sent: Wednesday, July 25, 2012 12:31 PM
To: OTspec
Subject: [mpeg-OTspec] New work on 3rd edition of the OFF (AHG kick-off)


Dear AHG members,

With this kick-off message, I would like to announce the start of the new work on the 3rd edition of the ISO/IEC 14496-22 "Open Font Format" that was approved at the MPEG meeting last week. I will create a new working draft merging the base document (previous 2nd  edition version from 2009) with all changes that were introduced by amendments and corrigendum and will make the new text available for you to review and comment.

I would also like to ask you to start thinking about new features, functionality and clarifications that you would like to propose to improve the text of the standard. In particular, I would like us to review the proposals that have already been submitted to this AHG in recent couple of years and discuss whether it would be reasonable and useful to incorporate them into the current working draft text. For this purpose, I have collected the references to member posts outlining newly proposed items (my apologies if I missed any, please review and contribute your ideas):

-          OTL feature suggestion: Required Contextual Forms <rclt> (http://tech.groups.yahoo.com/group/mpeg-OTspec/message/411)

-          Quality of OT Layout Tag registry (http://tech.groups.yahoo.com/group/mpeg-OTspec/message/635)

-          'post' table recommendations (http://tech.groups.yahoo.com/group/mpeg-OTspec/message/638)

-          Stylistic Sets (http://tech.groups.yahoo.com/group/mpeg-OTspec/message/642)

-          OTC filename extension (http://tech.groups.yahoo.com/group/mpeg-OTspec/message/643)

-          Supporting Unicode properties for vertical text layout (http://tech.groups.yahoo.com/group/mpeg-OTspec/message/648)

-          UTF encoding for 'name' table strings (http://tech.groups.yahoo.com/group/mpeg-OTspec/message/655)

-          Renaming "preferred" family (http://tech.groups.yahoo.com/group/mpeg-OTspec/message/657)

-          Panose field in OS/2 (http://tech.groups.yahoo.com/group/mpeg-OTspec/message/668) - recently resolved!

-          'name' table update (http://tech.groups.yahoo.com/group/mpeg-OTspec/message/714)

-          New 'cmap' format (http://tech.groups.yahoo.com/group/mpeg-OTspec/message/722)

-          Vertical ligatures (http://tech.groups.yahoo.com/group/mpeg-OTspec/message/734)

FYI - the next MPEG meeting will take place on October 15-19.

Thank you,
Vladimir



-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.aau.at/pipermail/mpeg-otspec/attachments/20120731/03a3ac07/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/x-ygp-stripped
Size: 322 bytes
Desc: image001.jpg
URL: <https://lists.aau.at/pipermail/mpeg-otspec/attachments/20120731/03a3ac07/attachment.bin>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/x-ygp-stripped
Size: 322 bytes
Desc: image002.jpg
URL: <https://lists.aau.at/pipermail/mpeg-otspec/attachments/20120731/03a3ac07/attachment-0001.bin>