<semantics> A collection of "topics", their relationships, and
information sources. A topic map captures the subjects of
which information sources speak, and the relationships between
them, in a way that is implementation independent.
A topic is a symbol within the computer that represents
something in the world such as the play Hamlet, the playwright
William Shakespeare, or the "authorship" relationship.
Topics can have names. They can also have occurrences, that
is, information resources that are considered to be relevant
in some way to their subject. Topics can play roles in
relationships.
Thus, topics have three kinds of characteristics: names,
sources, and roles played in relationships. The assignment of
such characteristics is considered to be valid within a
certain scope, or context.
Topic maps can be merged. Merging can take place at the
discretion of the user or application (at runtime), or may be
indicated by the topic map's author at the time of its
creation.
