Source: Noto Sans Math

U+21CB Leftwards Harpoon Over Rightwards Harpoon

U+21CB was added in Unicode version 1.1 in 1993. It belongs to the block U+2190 to U+21FF Arrows 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 no designated width in East Asian texts. In bidirectional text it acts as Other Neutral. When changing direction it is not mirrored. The word that U+21CB forms with similar adjacent characters prevents a line break inside it.

The CLDR project calls this character “leftwards harpoon over rightwards harpoon” for use in screen reading software.

The Wikipedia has the following information about this codepoint:

In a chemical reaction, chemical equilibrium is the state in which both the reactants and products are present in concentrations which have no further tendency to change with time, so that there is no observable change in the properties of the system. This state results when the forward reaction proceeds at the same rate as the reverse reaction. The reaction rates of the forward and backward reactions are generally not zero, but they are equal. Thus, there are no net changes in the concentrations of the reactants and products. Such a state is known as dynamic equilibrium.

Representations

System	Representation
Nº	8651
UTF-8	E2 87 8B
UTF-16	21 CB
UTF-32	00 00 21 CB
URL-Quoted	%E2%87%8B
HTML hex reference	⇋
Wrong windows-1252 Mojibake	â‡‹
HTML named entity	&ReverseEquilibrium;
HTML named entity	&leftrightharpoons;
HTML named entity	&lrhar;
L^AT_EX	\leftrightharpoons

Elsewhere

Complete Record

Property	Value
Age (age)	1.1 (1993)
Unicode Name (na)	LEFTWARDS HARPOON OVER RIGHTWARDS HARPOON
Unicode 1 Name (na1)	LEFT HARPOON OVER RIGHT HARPOON
Block (blk)	Arrows
General Category (gc)	Other Symbol
Script (sc)	Common
Bidirectional Category (bc)	Other Neutral
Combining Class (ccc)	Not Reordered
Decomposition Type (dt)	none
Decomposition Mapping (dm)	Leftwards Harpoon Over Rightwards Harpoon
Lowercase (Lower)	✘
Simple Lowercase Mapping (slc)	Leftwards Harpoon Over Rightwards Harpoon
Lowercase Mapping (lc)	Leftwards Harpoon Over Rightwards Harpoon
Uppercase (Upper)	✘
Simple Uppercase Mapping (suc)	Leftwards Harpoon Over Rightwards Harpoon
Uppercase Mapping (uc)	Leftwards Harpoon Over Rightwards Harpoon
Simple Titlecase Mapping (stc)	Leftwards Harpoon Over Rightwards Harpoon
Titlecase Mapping (tc)	Leftwards Harpoon Over Rightwards Harpoon
Case Folding (cf)	Leftwards Harpoon Over Rightwards Harpoon
ASCII Hex Digit (AHex)	✘
Alphabetic (Alpha)	✘
Bidi Control (Bidi_C)	✘
Bidi Mirrored (Bidi_M)	✘
Composition Exclusion (CE)	✘
Case Ignorable (CI)	✘
Changes When Casefolded (CWCF)	✘
Changes When Casemapped (CWCM)	✘
Changes When NFKC Casefolded (CWKCF)	✘
Changes When Lowercased (CWL)	✘
Changes When Titlecased (CWT)	✘
Changes When Uppercased (CWU)	✘
Cased (Cased)	✘
Full Composition Exclusion (Comp_Ex)	✘
Default Ignorable Code Point (DI)	✘
Dash (Dash)	✘
Deprecated (Dep)	✘
Diacritic (Dia)	✘
Emoji Modifier Base (EBase)	✘
Emoji Component (EComp)	✘
Emoji Modifier (EMod)	✘
Emoji Presentation (EPres)	✘
Emoji (Emoji)	✘
Extender (Ext)	✘
Extended Pictographic (ExtPict)	✘
FC NFKC Closure (FC_NFKC)	Leftwards Harpoon Over Rightwards Harpoon
Grapheme Cluster Break (GCB)	Any
Grapheme Base (Gr_Base)	✔
Grapheme Extend (Gr_Ext)	✘
Grapheme Link (Gr_Link)	✘
Hex Digit (Hex)	✘
Hyphen (Hyphen)	✘
ID Continue (IDC)	✘
ID Start (IDS)	✘
IDS Binary Operator (IDSB)	✘
IDS Trinary Operator and (IDST)	✘
IDSU (IDSU)	0
ID_Compat_Math_Continue (ID_Compat_Math_Continue)	0
ID_Compat_Math_Start (ID_Compat_Math_Start)	0
Ideographic (Ideo)	✘
InCB (InCB)	None
Indic Mantra Category (InMC)	—
Indic Positional Category (InPC)	NA
Indic Syllabic Category (InSC)	Other
Jamo Short Name (JSN)	—
Join Control (Join_C)	✘
Logical Order Exception (LOE)	✘
Math (Math)	✔
Noncharacter Code Point (NChar)	✘
NFC Quick Check (NFC_QC)	Yes
NFD Quick Check (NFD_QC)	Yes
NFKC Casefold (NFKC_CF)	Leftwards Harpoon Over Rightwards Harpoon
NFKC Quick Check (NFKC_QC)	Yes
NFKC_SCF (NFKC_SCF)	Leftwards Harpoon Over Rightwards Harpoon
NFKD Quick Check (NFKD_QC)	Yes
Other Alphabetic (OAlpha)	✘
Other Default Ignorable Code Point (ODI)	✘
Other Grapheme Extend (OGr_Ext)	✘
Other ID Continue (OIDC)	✘
Other ID Start (OIDS)	✘
Other Lowercase (OLower)	✘
Other Math (OMath)	✔
Other Uppercase (OUpper)	✘
Prepended Concatenation Mark (PCM)	✘
Pattern Syntax (Pat_Syn)	✔
Pattern White Space (Pat_WS)	✘
Quotation Mark (QMark)	✘
Regional Indicator (RI)	✘
Radical (Radical)	✘
Sentence Break (SB)	Other
Soft Dotted (SD)	✘
Sentence Terminal (STerm)	✘
Terminal Punctuation (Term)	✘
Unified Ideograph (UIdeo)	✘
Variation Selector (VS)	✘
Word Break (WB)	Other
White Space (WSpace)	✘
XID Continue (XIDC)	✘
XID Start (XIDS)	✘
Expands On NFC (XO_NFC)	✘
Expands On NFD (XO_NFD)	✘
Expands On NFKC (XO_NFKC)	✘
Expands On NFKD (XO_NFKD)	✘
Bidi Paired Bracket (bpb)	Leftwards Harpoon Over Rightwards Harpoon
Bidi Paired Bracket Type (bpt)	None
East Asian Width (ea)	neutral
Hangul Syllable Type (hst)	Not Applicable
ISO 10646 Comment (isc)	—
Joining Group (jg)	No_Joining_Group
Joining Type (jt)	Non Joining
Line Break (lb)	Alphabetic
Numeric Type (nt)	none
Numeric Value (nv)	not a number
Simple Case Folding (scf)	Leftwards Harpoon Over Rightwards Harpoon
Script Extension (scx)
Vertical Orientation (vo)	R