Adobe-Japan1-7 Subset Fonts

Per the previous article, the Adobe-Japan1-6 Character Collection specification will be updated to Adobe-Japan1-7 shortly after Japan’s new era name is announced. This article notes some of the changes that need to be considered as part of that update, and I am therefore soliciting feedback on the ideas that are presented below.

For OpenType Japanese fonts that already support Adobe-Japan1-6 in its entirety, meaning that all 23,058 glyphs are included, updating to Adobe-Japan1-7 is a relatively simply matter of adding two glyphs and its associated mappings, along with renaming the fonts to use an Adobe-Japan1-7 designator. Of course, not all fonts need to be updated to include the Adobe-Japan1-7 glyphs, and this article is meant to benefit Japanese font developers who plan to do so for some or all of their fonts.

To that end, the table in the OpenType Font Naming Conventions subsection of the OpenType Font Development section will need to be updated to the following:

Supplement Designator JIS2004-Savvy Designator /CIDFontName & Menu Name Examples
3 Std StdN KozMinStd-Regular, 小塚明朝 Std R & KozMinStdN-Regular, 小塚明朝 StdN R
4 Pro ProN KozMinPro-Regular, 小塚明朝 Pro R & KozMinProN-Regular, 小塚明朝 ProN R
5 Pr5 Pr5N KozMinPr5-Regular, 小塚明朝 Pr5 R & KozMinPr5N-Regular, 小塚明朝 Pr5N R
6 Pr6 Pr6N KozMinPr6-Regular, 小塚明朝 Pr6 R & KozMinPr6N-Regular, 小塚明朝 Pr6N R
7 Pr7 Pr7N KozMinPr7-Regular, 小塚明朝 Pr7 R & KozMinPr7N-Regular, 小塚明朝 Pr7N R

What is less clear is how to handle the Supplement 7 glyphs in the context of subset fonts, such as JIS90-savvy fonts that support only an earlier Supplement, or JIS2004-savvy fonts that include a small number of glyphs from higher Supplements. That is the purpose of this particular article.

Not all Japanese fonts include all 23,058 glyphs specified by Adobe-Japan1-6, and a very large number of them support only Adobe-Japan1-3, some of which include an additional 144 glyphs from Supplements 4 through 6 in order to be JIS2004-savvy. As an example, latest Hiragino (ヒラギノ) fonts as bundled with macOS support either Adobe-Japan1-3 or Adobe-Japan1-5, and in a JIS2004-savvy way. It takes a lot of time and effort to design the glyphs for a Japanese typeface, especially when over 23,000 glyphs may be required, and not all of those 23,000 glyphs are used very frequently.

To this end, there will be a strong desire to include the glyphs for the two-kanji square ligature that represents Japan’s forthcoming new era name in fonts that do not currently support Adobe-Japan1-6, and the following sections outline a plan for enabling this new character in existing fonts whose developers have no intention of fully supporting Adobe-Japan1-6.

JIS90-Savvy OpenType Fonts

Developing JIS90-savvy OpenType fonts has been relatively simple, because such fonts need to include only the glyphs from one of the defined Supplements. The most common ones support Adobe-Japan1-3 (9,453 glyphs), Adobe-Japan1-4 (15,444 glyphs), or Adobe-Japan1-5 (20,317 glyphs).

When considering Adobe-Japan1-7 and its two glyphs for supporting Japan’s forthcoming new era name that takes effect on 2019-05-01, Supplement 3 (aka “Std”) fonts require only CID+23058, which is the horizontal form. The glyphs for the vertical variants of the current and previous three era names are in Supplement 4, and are therefore treated as out-of-scope for Supplement 3 fonts. For Supplement 4 and higher fonts, CIDs 23058 and 23059 can simply be added. While the designator—Pro, Pr5, or Pr6—can remain as-is, the Supplement value as specified in the 'CFF ' table should be set to 7.

JIS2004-Savvy OpenType Fonts

The Adobe-Japan1-6 Character Collection specification includes the following table in the JIS2004-Savvy OpenType Fonts subsection of the OpenType Font Development section that specifies which glyphs from higher Supplements should be added to fonts that support an earlier Supplement in order to make them JIS2004-savvy:

Supplement Additional Glyphs Designator CIDs & CID Ranges
3 144 StdN 4—9354, 9779, 12101, 12870, 13320–13327, 13330, 13332–13333, 13335–13341, 13343, 13345–13355, 13358–13369, 13371, 13373–13382, 13385–13388, 13391–13400, 13402, 13460, 13495, 13538, 13624, 13650, 13673, 13731, 13803, 13860, 13893, 13915, 13949, 13964, 14013, 14066, 14074, 14111, 14116, 14196, 14272, 14290
5—16977, 17041, 18760, 19312, 19346, 20175, 20222, 20263–20296, 20301–20305, 20307, 20314
6—21072–21074
4 81 ProN 5—16413, 16444–16449, 16467–16468, 16889, 16905, 16977, 17014, 17041, 17168, 17205, 18759–18760, 19061, 19312, 19346, 20175, 20222, 20263–20296, 20299–20310, 20312–20315
6—21071–21074, 21558, 21933, 22010, 22920
5 10 Pr5N 6—21071–21074, 21371, 21558, 21722, 21933, 22010, 22920

Now, when we consider Adobe-Japan1-7 and its two glyphs, the following table illustrates how I propose that these subsets be adjusted:

Supplement Additional Glyphs Designator CIDs & CID Ranges
3 145 StdN 4—9354, 9779, 12101, 12870, 13320–13327, 13330, 13332–13333, 13335–13341, 13343, 13345–13355, 13358–13369, 13371, 13373–13382, 13385–13388, 13391–13400, 13402, 13460, 13495, 13538, 13624, 13650, 13673, 13731, 13803, 13860, 13893, 13915, 13949, 13964, 14013, 14066, 14074, 14111, 14116, 14196, 14272, 14290
5—16977, 17041, 18760, 19312, 19346, 20175, 20222, 20263–20296, 20301–20305, 20307, 20314
6—21072–21074
7—23058
4 83 ProN 5—16413, 16444–16449, 16467–16468, 16889, 16905, 16977, 17014, 17041, 17168, 17205, 18759–18760, 19061, 19312, 19346, 20175, 20222, 20263–20296, 20299–20310, 20312–20315
6—21071–21074, 21558, 21933, 22010, 22920
7—23058–23059
5 12 Pr5N 6—21071–21074, 21371, 21558, 21722, 21933, 22010, 22920
7—23058–23059

The main difference, of course, is that the Supplement 3 subset includes only CID+23058 from Supplement 7. As previously explained for JIS90-savvy fonts, the reason why CID+23059 does not need to be included is because the glyphs for the vertical variants of the current and three previous era names—U+337B ㍻, U+337C ㍼, U+337D ㍽ & U+337E ㍾—are in Supplement 4, but are not included in the Supplement 3 (aka “StdN”) subset definition. Their Supplement 4 CIDs are 12041 through 12044. I should also point out that the “StdN” glyph set definition—Adobe-Japan1-3 plus 144 additional glyphs from Supplements 4 through 6—has been stable for over 10 years, and if the vertical variants of the current and previous three era names were actually required, there would have been a non-zero number of customer reports requesting them to be added.

Lastly, it is prudent to reiterate that the specified Supplement value in the 'CFF ' table should be based on the highest CID value in the font. For example, an Adobe-Japan1-3 font that includes CID+23058 should specify “7” as its Supplement value, regardless of whether it is a “Std” or “StdN” font.

In closing, I welcome any and all feedback. We have time to consider other options, though the ones I proposed in this article seem to make the most sense.

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