U+1D55A "𝕚" Mathematical Double-Struck Small I Unicode Character

U+1D55A "𝕚" Mathematical Double-Struck Small I is a stylized lowercase letter i that belongs to the Mathematical Alphanumeric Symbols block, specifically designed for use in mathematical and scientific notation where a double-struck or blackboard bold font style is needed to denote special number sets or imaginary units. It is commonly employed as the imaginary unit in complex numbers, especially to avoid confusion with other uses of the standard italic "i". The character's glyph features a thickened, outlined appearance reminiscent of chalkboard writing, and it is primarily intended for semantic distinction rather than decorative purposes.

General Properties

Code Point	U+1D55A
Version Added	3.1
Name	Mathematical Double-Struck Small I
Block	Mathematical Alphanumeric Symbols
General Category	Lowercase Letter
Canonical Combining Class	Not Reordered
Bidirectional Class	Left To Right
Decomposition Type	Font
Decomposition Mapping	"i" U+0069 Latin Small Letter I

Encodings

HTML Decimal Encoding	𝕚
HTML Hex Encoding	𝕚
UTF-8 Encoding	0xF0 0x9D 0x95 0x9A
UTF-16 Encoding	0xD835 0xDD5A
UTF-32 Encoding	0x0001D55A
C/C++/Java Escape	\ud835\udd5a

Unicode Properties

NFC Quick Check	Yes
NFD Quick Check	Yes
Numeric Type	None
Numeric Value	NaN
Line Break	Alphabetic
Lowercase	Yes
Cased	Yes
Changes When NFKC Casefolded	Yes
NFKC Casefold	"i" U+0069 Latin Small Letter I
NFKC Simple Casefold	"i" U+0069 Latin Small Letter I
Script	Common
Script Extensions	Common
Indic Syllabic Category	Other
ID Start	Yes
XID Start	Yes
ID Continue	Yes
XID Continue	Yes
Soft Dotted	Yes
Alphabetic	Yes
Math	Yes
Other Math	Yes
Vertical Orientation	Rotated
Grapheme Base	Yes
Grapheme Cluster Break	Other
Word Break	Alphabetic letter
Sentence Break	Lower