U+2621 CAUTION SIGN: ☡ – Unicode

U+2621 was added to Unicode in version 1.1 (1993). It belongs to the block U+2600 to U+26FF Miscellaneous Symbols in the U+0000 to U+FFFF Basic Multilingual Plane.

This character is a Other Symbol and is commonly used, that is, in no specific script.

The glyph is not a composition. It has a Neutral East Asian Width. In bidirectional context it acts as Other Neutral and is not mirrored. In text U+2621 behaves as Alphabetic regarding line breaks. It has type Other for sentence and Other for word breaks. The Grapheme Cluster Break is Any.

The Wikipedia has the following information about this codepoint:

The dangerous bend or caution symbol ☡ (U+2621 ☡ CAUTION SIGN) was created by the Nicolas Bourbaki group of mathematicians and appears in the margins of mathematics books written by the group. It resembles a road sign that indicates a "dangerous bend" in the road ahead, and is used to mark passages tricky on a first reading or with an especially difficult argument.

Representations

System	Representation
Nº	9761
UTF-8	E2 98 A1
UTF-16	26 21
UTF-32	00 00 26 21
URL-Quoted	%E2%98%A1
HTML-Escape	☡
Wrong windows-1252 Mojibake	â¡

Elsewhere

Complete Record

Property	Value
Age	1.1 (1993)
Unicode Name	CAUTION SIGN
Unicode 1 Name	—
Block	Miscellaneous Symbols and Pictographs
General Category	Other Symbol
Script	Common
Bidirectional Category	Other Neutral
Combining Class	Not Reordered
Decomposition Type	None
Decomposition Mapping	Caution Sign
Lowercase	✘
Simple Lowercase Mapping	Caution Sign
Lowercase Mapping	Caution Sign
Uppercase	✘
Simple Uppercase Mapping	Caution Sign
Uppercase Mapping	Caution Sign
Simple Titlecase Mapping	Caution Sign
Titlecase Mapping	Caution Sign
Case Folding	Caution Sign
ASCII Hex Digit	✘
Alphabetic	✘
Bidi Control	✘
Bidi Mirrored	✘
Composition Exclusion	✘
Case Ignorable	✘
Changes When Casefolded	✘
Changes When Casemapped	✘
Changes When NFKC Casefolded	✘
Changes When Lowercased	✘
Changes When Titlecased	✘
Changes When Uppercased	✘
Cased	✘
Full Composition Exclusion	✘
Default Ignorable Code Point	✘
Dash	✘
Deprecated	✘
Diacritic	✘
Emoji Modifier Base	✘
Emoji Component	✘
Emoji Modifier	✘
Emoji Presentation	✘
Emoji	✘
Extender	✘
Extended Pictographic	✔
FC NFKC Closure	Caution Sign
Grapheme Cluster Break	Any
Grapheme Base	✔
Grapheme Extend	✘
Grapheme Link	✘
Hex Digit	✘
Hyphen	✘
ID Continue	✘
ID Start	✘
IDS Binary Operator	✘
IDS Trinary Operator and	✘
Ideographic	✘
Indic Mantra Category	—
Indic Positional Category	NA
Indic Syllabic Category	Other
Jamo Short Name	—
Join Control	✘
Logical Order Exception	✘
Math	✘
Noncharacter Code Point	✘
NFC Quick Check	Yes
NFD Quick Check	Yes
NFKC Casefold	Caution Sign
NFKC Quick Check	Yes
NFKD Quick Check	Yes
Other Alphabetic	✘
Other Default Ignorable Code Point	✘
Other Grapheme Extend	✘
Other ID Continue	✘
Other ID Start	✘
Other Lowercase	✘
Other Math	✘
Other Uppercase	✘
Prepended Concatenation Mark	✘
Pattern Syntax	✔
Pattern White Space	✘
Quotation Mark	✘
Regional Indicator	✘
Radical	✘
Sentence Break	Other
Soft Dotted	✘
Sentence Terminal	✘
Terminal Punctuation	✘
Unified Ideograph	✘
Variation Selector	✘
Word Break	Other
White Space	✘
XID Continue	✘
XID Start	✘
Expands On NFC	✘
Expands On NFD	✘
Expands On NFKC	✘
Expands On NFKD	✘
Bidi Paired Bracket	Caution Sign
Bidi Paired Bracket Type	None
East Asian Width	Neutral
Hangul Syllable Type	Not Applicable
ISO 10646 Comment	—
Joining Group	No_Joining_Group
Joining Type	Non Joining
Line Break	Alphabetic
Numeric Type	None
Numeric Value	not a number
Simple Case Folding	Caution Sign
Script Extension
Vertical Orientation	U