U+2111 "ℑ" Black-Letter Capital I Unicode Character

U+2111 "ℑ" Black-Letter Capital I is a typographic symbol derived from medieval Fraktur or blackletter scripts, traditionally used in mathematics to represent the imaginary part of a complex number, often in conjunction with the notation ℜ for the real part. It appears as an ornate, calligraphic capital I with thick, angular strokes and decorative flourishes, distinct from standard roman or italic fonts. This character is encoded in the Letterlike Symbols block of Unicode and has specific uses in fields like complex analysis and physics, where it helps denote the imaginary unit or the imaginary component of a function while maintaining a clear visual distinction from ordinary text.

General Properties

Code Point	U+2111
Version Added	1.1
Name	Black-Letter Capital I
Unicode 1.0 Name	Black-Letter I
Block	Letterlike Symbols
General Category	Uppercase Letter
Canonical Combining Class	Not Reordered
Bidirectional Class	Left To Right
Decomposition Type	Font
Decomposition Mapping	"I" U+0049 Latin Capital Letter I

Encodings

HTML Decimal Encoding	ℑ
HTML Hex Encoding	ℑ
UTF-8 Encoding	0xE2 0x84 0x91
UTF-16 Encoding	0x2111
UTF-32 Encoding	0x00002111
C/C++/Java Escape	\u2111

Unicode Properties

NFC Quick Check	Yes
NFD Quick Check	Yes
Numeric Type	None
Numeric Value	NaN
Line Break	Alphabetic
Uppercase	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
Alphabetic	Yes
Math	Yes
Other Math	Yes
Vertical Orientation	Rotated
Grapheme Base	Yes
Grapheme Cluster Break	Other
Word Break	Alphabetic letter
Sentence Break	Upper