All terms not defined here shall be as defined in the Unicode Standard. It can take on two abstract 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. Where characters are defined to have an ambiguous East Asian Width, their East Asian Width can be resolved to narrow or wide depending on additional information not contained in the character code.
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.