U+1D431 "𝐱" Mathematical Bold Small X Unicode Character

U+1D431 "𝐱" Mathematical Bold Small X is a typographic variant of the standard lowercase letter 'x', specifically designed for mathematical and scientific notation where a bold weight is required to distinguish variables, vectors, or other elements within complex formulas. It belongs to the "Mathematical Alphanumeric Symbols" block, which was added to Unicode to provide dedicated characters for mathematical formatting instead of relying on simple font styling. This allows text processing in plain text environments, such as in publishing or software algorithms, to reliably preserve the intended mathematical meaning and visual structure without losing formatting information.

General Properties

Code Point	U+1D431
Version Added	3.1
Name	Mathematical Bold Small X
Block	Mathematical Alphanumeric Symbols
General Category	Lowercase Letter
Canonical Combining Class	Not Reordered
Bidirectional Class	Left To Right
Decomposition Type	Font
Decomposition Mapping	"x" U+0078 Latin Small Letter X

Encodings

HTML Decimal Encoding	𝐱
HTML Hex Encoding	𝐱
UTF-8 Encoding	0xF0 0x9D 0x90 0xB1
UTF-16 Encoding	0xD835 0xDC31
UTF-32 Encoding	0x0001D431
C/C++/Java Escape	\ud835\udc31

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	"x" U+0078 Latin Small Letter X
NFKC Simple Casefold	"x" U+0078 Latin Small Letter X
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	Lower