U+210D "ℍ" Double-Struck Capital H Unicode Character

U+210D "ℍ" Double-Struck Capital H is a typographic symbol belonging to the set of double-struck (blackboard bold) letters, commonly used in mathematics to denote the set of quaternions, which are a number system extending complex numbers. This character is part of the Letterlike Symbols block in Unicode, designed to visually mimic handwriting conventions where special number sets are written with bold or double-struck letters for clarity. Its inclusion in Unicode ensures consistent representation across digital platforms, allowing mathematicians and scientists to precisely denote quaternions in academic papers, online forums, and digital documents without relying on font tricks or formatting workarounds.

General Properties

Code Point	U+210D
Version Added	1.1
Name	Double-Struck Capital H
Unicode 1.0 Name	Double-Struck H
Block	Letterlike Symbols
General Category	Uppercase Letter
Canonical Combining Class	Not Reordered
Bidirectional Class	Left To Right
Decomposition Type	Font
Decomposition Mapping	"H" U+0048 Latin Capital Letter H

Encodings

HTML Decimal Encoding	ℍ
HTML Hex Encoding	ℍ
UTF-8 Encoding	0xE2 0x84 0x8D
UTF-16 Encoding	0x210D
UTF-32 Encoding	0x0000210D
C/C++/Java Escape	\u210d

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	"h" U+0068 Latin Small Letter H
NFKC Simple Casefold	"h" U+0068 Latin Small Letter H
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