U+FFED HALFWIDTH BLACK SQUARE

U+FFED was added to Unicode in version 1.1 (1993). It belongs to the block Halfwidth and Fullwidth Forms in the Basic Multilingual Plane.

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

The glyph is a Narrow composition of the glyphs . It has a Halfwidth East Asian Width. In bidirectional context it acts as Other Neutral and is not mirrored. The glyph can, under circumstances, be confused with 2 other glyphs. In text U+FFED 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:

In CJK (Chinese, Japanese and Korean) computing, graphic characters are traditionally classed into fullwidth (in Taiwan and Hong Kong: 全形; in CJK and Japanese: 全角) and halfwidth (in Taiwan and Hong Kong: 半形; in CJK and Japanese: 半角) characters. With fixed-width fonts, a halfwidth character occupies half the width of a fullwidth character, hence the name.

In the days of computer terminals and text mode computing, characters were normally laid out in a grid, often 80 columns by 24 or 25 lines. Each character was displayed as a small dot matrix, often about 8 pixels wide, and an SBCS (single byte character set) was generally used to encode characters of western languages.

For a number of practical and aesthetic reasons, Han characters would need to be twice as wide as these fixed-width SBCS characters. These "fullwidth characters" were typically encoded in a DBCS (double byte character set), although less common systems used other variable-width character sets that used more bytes per character.

Halfwidth and Fullwidth Forms is also the name of a Unicode block U+FF00–FFEF.