U+1D408 "𝐈" Mathematical Bold Capital I Unicode Character

Unicode Version 17.0

𝐈

U+1D408 "𝐈" Mathematical Bold Capital I is a typographic variant of the standard Latin capital letter I, designed for use in mathematical and scientific notation to represent variables, matrices, vectors, or other quantities in a bold typeface. It belongs to the Mathematical Alphanumeric Symbols block, which provides distinct letterforms to avoid confusion with ordinary text and to maintain clarity in complex equations. This character is not intended for use in general prose but is instead reserved for formatting mathematical expressions, often appearing in contexts where a bold upright style is required, such as for identity matrices or constants. Its encoding allows digital representations to preserve the semantic distinction between mathematical symbols and regular alphabet letters.

General Properties

Code Point U+1D408
Version Added 3.1
Name Mathematical Bold Capital I
Block Mathematical Alphanumeric 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 0xF0 0x9D 0x90 0x88
UTF-16 Encoding 0xD835 0xDC08
UTF-32 Encoding 0x0001D408
C/C++/Java Escape \ud835\udc08

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