Some initial Adobe-Japan1-6 versus UTR #50 thoughts…

UTC (Unicode Technical Committee) Meeting #136 took place last week, and one of the significant outcomes was that UTR (Unicode Technical Report) #50 was advanced from Draft to Approved status. Congratulations to Koji ISHII (石井宏治), its editor, and also to Eric Muller, who took the initiative to start this project and served as its first editor.

While there is still some amount of editorial work to do before UTR #50 can be released in approved form, the minor adjustments to its property values—R, Tr, Tu, and U—are known, at least to me and others who attended last week’s UTC meeting. This allows me to begin the process of examining the ‘vert‘ and ‘vrt2‘ GSUB feature definitions in Adobe-Japan1-6 and our other public ROSes, to include those fonts that use the special-purpose Adobe-Identity-0 ROS such as Kazuraki (かづらき), and to determine whether any adjustments need to be made, and how to define the soon-to-be-registered and tentatively-tagged ‘svrt’ GSUB feature.

The basic premise of how UTR #50 should influence vertical OpenType features is that vertical substitutions whose base characters have the property value Tr and Tu should be included in the ‘vert’ GSUB feature, along with those with the property value U whose vertical forms remain upright, and those whose base characters have the property value R (actual or implied from the font implementation) should be included in the ‘svrt’ GSUB feature.

Keep in mind that Unicode is a character encoding standard, and that the Adobe-Japan1-6 ROS and friends are glyph set standards. This means that there will be conflicts. However, all conflicts have resolutions. Some of the more interesting cases are detailed below:

  • Unicode includes a single, in terms of directionality, scissors character, U+2702 (BLACK SCISSORS), and is thus assigned the property value U. Adobe-Japan1-6, on the other hand, includes four glyphs for the scissors character, CIDs 12175 through 12178 (in the Supplement 4 region), which have directionality, and should thus be treated like arrows (property value R).
  • Unicode includes the basic set of half-width katakana (U+FF61 through U+FF9F), which are assigned property value R. Adobe-Japan1-6 additionally includes glyphs for extended half-width katakana (mainly dakuten- and handakuten-annotated versions), CIDs 391 through 421, which should be treated the same (property value R).
  • Perhaps more interesting is the complete set of half-width hiragana, which are not in Unicode, but included in Adobe-Japan1-6 as CIDs 515 through 598, which should be treated like half-width katakana, meaning property value R.

Anyway, I plan to write a new article about this topic as soon as some of these details are better known.

Back to work…

Comments are closed.