noncharacters leaves 1,111,998 code points available for use. Private-use code points are considered to be assigned characters, but they have no interpretation specified by the Unicode standard so any interchange of such characters requires an agreement between sender and receiver on their interpretation. There are three private-use areas in the Unicode codespace: Private Use Area: U+E000–U+F8FF (6,400 characters), Supplementary Private Use Area-A: U+F0000–U+FFFFD (65,534 characters), Supplementary Private Use Area-B: U+100000–U+10FFFD (65,534 characters). Graphic characters are characters defined by Unicode to have particular semantics, and either have a visible glyph shape or represent a visible space. As of Unicode 15.0 there are 149,014 graphic characters. Format characters are characters that do not have a visible appearance, but may have an effect on the appearance or behavior of neighboring characters. For example, and may be used to change the default shaping behavior of adjacent characters (e.g., to inhibit ligatures or request ligature formation). There are 172 format characters in Unicode 15.0. Sixty-five code points (U+0000–U+001F and U+007F–U+009F) are reserved as control codes, and correspond to the C0 and C1 control codes defined in ISO/IEC 6429. U+0009 (Tab), U+000A (Line Feed), and U+000D (Carriage Return) are widely used in Unicode-encoded texts. In practice the C1 code points are often improperly-translated (mojibake) as the legacy Windows-1252 characters used by some English and Western European texts. Graphic characters, format characters, control code characters, and private use characters are known collectively as assigned characters. Reserved code points are those code points which are available for use, but are not yet assigned. As of Unicode 15.0 there are 825,279 reserved code points. Abstract characters The set of graphic and format characters defined by Unicode does not correspond directly to the repertoire of abstract characters that is representable under Unicode. Unicode encodes characters by associating an abstract character with a particular code point. However, not all abstract characters are encoded as a single Unicode character, and some abstract characters may be represented in Unicode by a sequence of two or more characters. For example, a Latin small letter "i" with an ogonek, a dot above, and an acute accent, which is required in Lithuanian, is represented by the character sequence U+012F, U+0307, U+0301. Unicode maintains a list of uniquely named character sequences for abstract characters that are not directly encoded in Unicode. All graphic, format, and private use characters have a unique and immutable name by which they