U+FF3F "＿" Fullwidth Low Line Unicode Character

U+FF3F "＿" Fullwidth Low Line is a typographic symbol that represents a fullwidth version of the standard underscore, designed to occupy the same horizontal space as a CJK (Chinese, Japanese, and Korean) ideographic character, typically double the width of a typical Latin letter. It is primarily used in East Asian text systems to create visual underlining or placeholder effects in monospaced environments, such as in forms, programming, or text art, where alignment with fullwidth characters is crucial. This code point is part of the Halfwidth and Fullwidth Forms block in Unicode, which provides compatibility with older character encodings like Shift JIS or Big5, ensuring consistent rendering across diverse digital contexts.

General Properties

Code Point	U+FF3F
Version Added	1.1
Name	Fullwidth Low Line
Unicode 1.0 Name	Fullwidth Spacing Underscore
Block	Halfwidth and Fullwidth Forms
General Category	Connector Punctuation
Canonical Combining Class	Not Reordered
Bidirectional Class	Other Neutral
Decomposition Type	Wide
Decomposition Mapping	"_" U+005F Low Line

Encodings

HTML Decimal Encoding	＿
HTML Hex Encoding	＿
UTF-8 Encoding	0xEF 0xBC 0xBF
UTF-16 Encoding	0xFF3F
UTF-32 Encoding	0x0000FF3F
C/C++/Java Escape	\uff3f

Unicode Properties

NFC Quick Check	Yes
NFD Quick Check	Yes
Numeric Type	None
Numeric Value	NaN
Line Break	Ideographic
East Asian Width	Fullwidth
Changes When NFKC Casefolded	Yes
NFKC Casefold	"_" U+005F Low Line
NFKC Simple Casefold	"_" U+005F Low Line
Script	Common
Script Extensions	Common
Indic Syllabic Category	Other
ID Continue	Yes
XID Continue	Yes
Vertical Orientation	Transformed Rotated
Grapheme Base	Yes
Grapheme Cluster Break	Other
Word Break	Extend Num Let
Sentence Break	Other