2022 Top Ten List: Why Support Beyond-BMP Code Points?

By Dr Ken Lunde

Beyond-BMP code points refer to code points that are outside the BMP (Basic Multilingual Plane) of the Unicode Standard, specifically Planes 1 through 16, each of which includes 65,534 assignable code points. Of those 16 beyond-BMP planes, only six are currently in use, in terms of having assigned code points: Plane 1 (SMP or Supplementary Multilingual Plane), Plane 2 (aka SIP or Supplementary Ideographic Plane), Plane 3 (aka TIP or Tertiary Ideographic Plane), Plane 14 (aka SSP or Supplementary Special-purpose Plane), Plane 15 (aka SPUA-A or Supplementary Private Use Area-A), and Plane 16 (aka SPUA-B or Supplementary Private Use Area-B).

I first came up with the idea for this Top Ten List over 10 years ago, which was prompted by some environments that still supported only BMP code points. The idea, of course, was to motivate the developers of such environments to support code points beyond the BMP by providing an enumerated list of reasons to do so. And yes, there are still some environments that support only BMP code points, such as the VivaDesigner app.

This primary purpose of this article is to show the 12-frame animated GIF that is provided below, which presents the Top Ten List in reverse order, counting down from 10 to 1. So, without further ado, I present to you 2022 Top Ten List: Why Support Beyond-BMP Code Points?

Many versions of this Top Ten List have been produced—and presented—over the years, and each new version of the Unicode Standard provides an opportunity to update it. As this Top Ten List shows, East Asian regional standards serve as half of its items, and sometimes need to be updated if there are changes that are manifested outside of the BMP. For example, in this 2022 update, two additional ideographs in Hong Kong SCS are encoded in Extensions E and F (Plane 2), which increased the figure to 1,706.

Presenting this Top Ten List is always fun, and takes only a few minutes. I first presented it on 2010-10-19 during IUC34 (34th Internationalization & Unicode Conference), and made it available on 2011-05-27 via the now-static CJK Type Blog. Updated versions were made available as new CJK Type Blog articles on 2014-04-03 and 2017-11-27. The 2020 version was tweeted on 2020-11-25 as an animated GIF.

I also presented combined Top Ten Lists—Why Support Beyond-BMP Code Points? and Reasons To Abandon Shift-JIS Encoding—on 2016-10-24 during a CITPC panel discussion at Microsoft’s HQ in Tōkyō, Japan, and on 2016-11-03 during IUC40.

About the Author

Dr Ken Lunde has worked for Apple as a Font Developer since 2021-08-02 (and was in the same role as a contractor from 2020-01-16 through 2021-07-30), is the author of CJKV Information Processing Second Edition (O’Reilly Media, 2009), and earned BA (1987), MA (1988), and PhD (1994) degrees in linguistics from The University of Wisconsin-Madison. Prior to working at Apple, he worked at Adobe for over twenty-eight years — from 1991-07-01 to 2019-10-18 — specializing in CJKV Type Development, meaning that he architected and developed fonts for East Asian typefaces, along with the standards and specifications on which they are based. He architected and developed the Adobe-branded “Source Han” (Source Han Sans, Source Han Serif, and Source Han Mono) and Google-branded “Noto CJK” (Noto Sans CJK and Noto Serif CJK) open source Pan-CJK typeface families that were released in 2014, 2017, and 2019, and published over 300 articles on Adobe’s now-static CJK Type Blog. Ken serves as the Unicode Consortium’s IVD (Ideographic Variation Database) Registrar, attends UTC and IRG meetings, participates in the Unicode Editorial Committee, became an individual Unicode Life Member in 2018, received the 2018 Unicode Bulldog Award, was a Unicode Technical Director from 2018 to 2020, became a Vice-Chair of the Emoji Subcommittee in 2019, published UTN #43 (Unihan Database Property “kStrange”) in 2020, and became the Chair of the CJK & Unihan Group in 2021. He and his wife, Hitomi, are proud owners of a His & Hers pair of acceleration-boosted 2018 LR Dual Motor AWD Tesla Model 3 EVs.