Note: the first 12 historic IDC (encoded long before current Unicode 15.1) are still not part of Noto Symbols or Noto Symbols2. They are currently included only in
However these 17 IDC characters are generic symbols that are not specifically restricted to CJK: they also have use for describing other non-CJK scripts, including Tangut/Katakana/Bopomofo/Hangul characters (where they are used for cross-references in the UniHan database), and may be needed as well for Hentaigana (included with Hiragana/Katakana in Noto CJK fonts, where there are still many characters needed for Japanese scripts extensions allocated in newer blocks), and classical Yi logosyllabic characters (still not encoded in Unicode, where only the modern Yi syllabary for the Nuoso language is standardized), and other Asian scripts like Small Khitan and Large Khitan, and possibly for hierographic scripts, and for complex/decorative/historic/author-specific ligatures in European or Arabic scripts (that cannot be supported by encoding them as combining sequences, but only as images, possibly non-free but still needing free descriptions: e.g. autographs from specific authors). They can also better describe various typographic arrangements in ideographic squares of letters from other scripts (e.g. Japanese or Korean symbols based on components from Latin/Greek/Hiragana/Katakana/Bopomofo/Hangul letters, sometimes mixed with other components from CJK radicals or strokes).
I think they could be integrated in Noto Sans Symbols(2), possibly as well in Noto Mono, because their design is very simple and there are not a lot of them. Their design should be independent of CJK variants (HK/JP/KR/SC/TC) and calligraphic styles, their stroke weight is uniform and they should not be italicized, keeping them only with perfectly square fullwidth metrics, fitting as well with box drawing characters or other geometric shapes.
Unicode: DerivedAge.txt
# Age=V15_1
# Newly assigned in Unicode 15.1.0 (September, 2023)
2FFC..2FFF ; 15.1 # [4] IDEOGRAPHIC DESCRIPTION CHARACTER SURROUND FROM RIGHT..IDEOGRAPHIC DESCRIPTION CHARACTER ROTATION
31EF ; 15.1 # IDEOGRAPHIC DESCRIPTION CHARACTER SUBTRACTION
2EBF0..2EE5D ; 15.1 # [622] CJK UNIFIED IDEOGRAPH-2EBF0..CJK UNIFIED IDEOGRAPH-2EE5D
U+2FFC-2FFF, U+31EF: Five additional "Ideographic description characters", newly assigned in Unicode 15.1.0 (September, 2023). Reference: https://www.unicode.org/charts/PDF/U2FF0.pdf https://www.unicode.org/charts/PDF/U31C0.pdf
Example free glyphs (named "U+xxxx.svg") available on: https://commons.wikimedia.org/wiki/Category:Unicode_2FF0-2FFF_Ideographic_Description_Characters https://commons.wikimedia.org/wiki/Category:Unicode_31C0-31EF_CJK_Strokes (SVG format, with minimal overhead but with precise metrics, optimized manually, freely licenced under CC0, ask me if you want another explicit licence/permission: I hereby grant the additional SIL Open Font Licence, if you need it for Noto fonts)
Note: the first 12 historic IDC (encoded long before current Unicode 15.1) are still not part of Noto Symbols or Noto Symbols2. They are currently included only in
However these 17 IDC characters are generic symbols that are not specifically restricted to CJK: they also have use for describing other non-CJK scripts, including Tangut/Katakana/Bopomofo/Hangul characters (where they are used for cross-references in the UniHan database), and may be needed as well for Hentaigana (included with Hiragana/Katakana in Noto CJK fonts, where there are still many characters needed for Japanese scripts extensions allocated in newer blocks), and classical Yi logosyllabic characters (still not encoded in Unicode, where only the modern Yi syllabary for the Nuoso language is standardized), and other Asian scripts like Small Khitan and Large Khitan, and possibly for hierographic scripts, and for complex/decorative/historic/author-specific ligatures in European or Arabic scripts (that cannot be supported by encoding them as combining sequences, but only as images, possibly non-free but still needing free descriptions: e.g. autographs from specific authors). They can also better describe various typographic arrangements in ideographic squares of letters from other scripts (e.g. Japanese or Korean symbols based on components from Latin/Greek/Hiragana/Katakana/Bopomofo/Hangul letters, sometimes mixed with other components from CJK radicals or strokes).
I think they could be integrated in Noto Sans Symbols(2), possibly as well in Noto Mono, because their design is very simple and there are not a lot of them. Their design should be independent of CJK variants (HK/JP/KR/SC/TC) and calligraphic styles, their stroke weight is uniform and they should not be italicized, keeping them only with perfectly square fullwidth metrics, fitting as well with box drawing characters or other geometric shapes.
Unicode: DerivedAge.txt