Glossary U

Unicode Standard

An international computer coding system published in 1990 by the Unicode Consortium, an organization of software professionals and major computing firms and institutions. In 1993 Version 1.0 of the Unicode Standard was replaced by the ISO/IEC (International Organization for Standardization/ International Electrotechnical Commission) 10646-1 Information Technology- Universal Multiple-Octet Coded Character Set (UCS), which is based on the Unicode Standard. The present edition of the ISO/IEC character set provides codes for characters used in the world's major written languages (scripts); it also includes additional symbols and typographic elements used in various disciplines, as well as characters that represent control sequences (such as paragraph return, backspace, and tab) that serve in the presentation of text. Future editions will include characters that supplement character sets already encoded and characters for additional languages, including historical scripts.

unit system

A system of measurement used in type design and typesetting in which each unit is typically equal to a specific fraction of the em. The size of a unit is relative to the type size being set; therefore, the number of units in an em remains the same at every type size, but the measurement of the unit changes according to the type size. Since the invention of mechanized metal typesetting, unit systems have been used to measure the spaces characters occupy (the measurement of these spaces being known as character widths, set widths, or sometimes unit values).

In some contemporary software, units also are used to measure other character dimensions and to determine the amount of space to add or subtract space to improve spacing between character pairs (kerning) or to add or subtract globally between the letters in words or passages of text (tracking, or uniform letter spacing). Relative unit systems that have been used in the manufacture of type include 18, 36, 54, 72, 96, and 108. Some recent systems use 1,000 units or more to the em. See also em, width, width value.

unit value

See width value.

unjustified text

See ragged right, ragged left.

uppercase letters

See capitals.