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476 Glossary

User model The user model defi nes the types of users of the interface and the relevant attributes
of those users. Its main purpose is to infl uence interface generation. It is not designed to be a
model of the mental state of the user at a particular time during the interaction.
Value An ideal accepted by some individual or group. The quality (positive or negative) that
renders something desirable or valuable.
Variety The total number of possible states of a system or an element of a system. It is a measure
of the complexity of the system. The total number of distinguishable states, that is, dependent
on the observational powers of a given observer. A useful managerial measure that conveys the
amount of requisite variety that will be required to model the system (and to base decisions on).

Virtualness “ As-if reality, ” an object that has an effect and shows behavior without physically
existing in reality.
Virtual organization Structure in which organization members in different locations work
together using e-mail, phone, fax, and other communication methods; a cluster of organizations
united by a series of electronic linkages.
Weak incentive A weak incentive is an incentive that is does not encourage maximization of
an objective, because it is ambiguous or lends itself to “ satisfi cing ” instead of optimizing.

Wiki Wiki wiki is a Hawaiian term meaning “ quick ” or “ super fast, ” and wiki became a term for
a web site or other hypertext document collection that gives users the ability to add content, as
on an Internet forum, but also allows this content to be edited by other users. The term can also
refer to collaborative software used to create such a web site.
XML eXtensible markup language. A subset of SGML constituting a particular text markup
language for interchange of structured data. The unicode standard is the reference character set
for XML content. XML is a trademark of the World Wide Web Consortium. A fl exible way to
create standard information formats and share both the format and the data on the World Wide
Web.