Source: Noto Sans

U+1D66 Greek Subscript Small Letter Beta

U+1D66 was added in Unicode version 4.0 in 2003. It belongs to the block U+1D00 to U+1D7F Phonetic Extensions in the U+0000 to U+FFFF Basic Multilingual Plane.

This character is a Modifier Letter and is mainly used in the Greek script.

The glyph is a subscript version of the glyph Greek Small Letter Beta. It has no designated width in East Asian texts. In bidirectional text it is written from left to right. When changing direction it is not mirrored. The word that U+1D66 forms with similar adjacent characters prevents a line break inside it.

The Wikipedia has the following information about this codepoint:

Unicode has subscripted and superscripted versions of a number of characters including a full set of Arabic numerals. These characters allow any polynomial, chemical and certain other equations to be represented in plain text without using any form of markup like HTML or TeX.
The World Wide Web Consortium and the Unicode Consortium have made recommendations on the choice between using markup and using superscript and subscript characters:

When used in mathematical context (MathML) it is recommended to consistently use style markup for superscripts and subscripts […] However, when super and sub-scripts are to reflect semantic distinctions, it is easier to work with these meanings encoded in text rather than markup, for example, in phonetic or phonemic transcription.

Representations

System	Representation
Nº	7526
UTF-8	E1 B5 A6
UTF-16	1D 66
UTF-32	00 00 1D 66
URL-Quoted	%E1%B5%A6
HTML hex reference	ᵦ
Wrong windows-1252 Mojibake	â—Œáµ¦
Encoding: GB18030 (hex bytes)	81 35 DF 30

Elsewhere

Complete Record

Property	Value
Age (age)	4.0 (2003)
Unicode Name (na)	GREEK SUBSCRIPT SMALL LETTER BETA
Unicode 1 Name (na1)	—
Block (blk)	Phonetic Extensions
General Category (gc)	Modifier Letter
Script (sc)	Greek
Bidirectional Category (bc)	Left To Right
Combining Class (ccc)	Not Reordered
Decomposition Type (dt)	subscript
Decomposition Mapping (dm)	Greek Small Letter Beta
Lowercase (Lower)	✔
Simple Lowercase Mapping (slc)	Greek Subscript Small Letter Beta
Lowercase Mapping (lc)	Greek Subscript Small Letter Beta
Uppercase (Upper)	✘
Simple Uppercase Mapping (suc)	Greek Subscript Small Letter Beta
Uppercase Mapping (uc)	Greek Subscript Small Letter Beta
Simple Titlecase Mapping (stc)	Greek Subscript Small Letter Beta
Titlecase Mapping (tc)	Greek Subscript Small Letter Beta
Case Folding (cf)	Greek Subscript Small Letter Beta
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)	Greek Subscript Small Letter Beta
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)	✘
Modifier Combining Mark (MCM)	✘
Math (Math)	✘
Noncharacter Code Point (NChar)	✘
NFC Quick Check (NFC_QC)	Yes
NFD Quick Check (NFD_QC)	Yes
NFKC Casefold (NFKC_CF)	Greek Small Letter Beta
NFKC Quick Check (NFKC_QC)	No
NFKC_SCF (NFKC_SCF)	Greek Small Letter Beta
NFKD Quick Check (NFKD_QC)	No
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)	Lower
Soft Dotted (SD)	✘
Sentence Terminal (STerm)	✘
Terminal Punctuation (Term)	✘
Unified Ideograph (UIdeo)	✘
Variation Selector (VS)	✘
Word Break (WB)	Alphabetic Letter
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)	Greek Subscript Small Letter Beta
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)	Greek Subscript Small Letter Beta
Script Extension (scx)
Vertical Orientation (vo)	R