IVS (Ideographic Variation Sequence) support in OSes
Finally. Yesterday, Friday, August 28th, 2009 is significant, at least for me, in that it represents the release date for Mac OS X Version 10.6 (aka, Snow Leopard). What is important about Snow Leopard is that it is the first OS that provides built-in support for IVSes (Ideographic Variation Sequences). Up until now, IVSes had been supported in specific Adobe products, such as Acrobat Version 9.0 and Adobe Reader Version 9.0 in the context of Forms, Flash Player Version 10, and InDesign CS4.
For those who are unaware of IVSes, they represent standardized Unicode behavior that allows otherwise unencoded variants of CJK Unified Ideographs to be represented using “plain text” that survives conditions that would cause rich text to fail. IVSes are registered via IVD (Ideographic Variation Database) Collections. The first IVD Collection to be registered at the end of 2007, was Adobe-Japan1, and is currently aligned with the Adobe-Japan1-6 character collection. See: http://www.unicode.org/ivd/
OpenType Japanese fonts can be IVS-enabled by building a Format 14 ‘cmap’ subtable. The AFDKO tools (in particular, MakeOTF and spot) are IVS-savvy, as well as DTL OTMaster (and the Light version).