We've just published another minor-version update of the OpenType spec: OpenType 1.8.2
This update was primarily aimed at refinements related to OpenType Font Variations, but there were other non-variations-related changes as well.
- Axes of design variation (weight, width, etc.), previously described in the 'fvar' chapter, are now described in a dedicated set of pages, the OpenType Design-Variation Axis Tag Registry
. This was done because these are relevant for non-variable as well as variable fonts, and to facilitate registration of new axis tags in the future.
- 'fvar': A new axis flag has been defined, HIDDEN_AXIS. This was defined to allow new font-picker user interfaces in applications to anticipate this or other future flags that may provide recommendations on how to present font options in the UI.
- 'gvar': The "IUP" algorithm (for inferring deltas for in-referenced points) has been revised to cover specific cases that were undefined, leading to inconsistent behaviours across platforms.
- 'STAT' (now version 1.2): Added a new axis value table format, format 4, which will allow named instances of some variable fonts to be supported better in older applications that were not designed to support families with an open-ended set of axis possibilities.
- CFF2: The FontMatrix operator has been constrained, and restricted to use in a Top DICT only.
- OT Layout scripts/language systems: A constraint on use of language system tags with 'DFLT' script has been relaxed.
There were also several errors corrected and details clarified, as well as many editorial changes, including changes to structure or field names for better consistency across the spec.
For more complete details on changes, see the change log
A note to font tool developers: all but a few chapters were revised to include anchors for all sections, table/record/enumeration descriptions, and individual fields, allowing you to offer users links to very specific parts of the spec.