All terms not defined here shall be as defined in the Unicode Standard. East Asian Width - in the context of interoperating with East Asian legacy character encodings and implementing East Asian typography, character width is an abstract concept. It can take on two values, narrow and wide . However, the actual display width of a glyph is given by the font and may be further adjusted by layout. An important class of fixed width legacy fonts contains glyphs of just two widths with the wider glyphs twice as wide as the narrower glyphs.
Ambiguous characters require context to resolve their width.
Private Use characters are considered ambiguous, since additional information is required to know whether they should be treated as wide or narrow. In particular, half-width punctuation behaves in some important ways like ideographic punctuation. Neutral characters do not occur in legacy East Asian character sets. By extension, they also do not occur in East Asian typography. For example, there is no traditional Japanese way of typesetting Devanagari.