Topic Maps are one potential way of implementing Semantic Web capabilities. They are an ISO standard (ISO/IEC 13250) which has been re-expressed as an XML application (http://www.topicmaps.org/xtm/index.html). The idea for Topic Maps originated in the document indexing community, but the resulting framework is capable of representing any ontological framework.
A Topic Map consists of:
· Topics, which are “subjects of discourse”, i.e. anything about which you might want to make assertions
· Associations, which are connections between two or more Topics
· Occurrences, which contain links to real-world resources which instantiate a Topic
Topic Maps do not need to contain any Occurrences: they can simply be abstract models of an area of discourse.
In the context of museum information, Associations allow us to express assertions about relationships between objects, people, places, events, etc. In other words, they provide a mechanism for describing the historical and cultural context of these entities.
Topics are identified in two ways: informally through Names, and more formally through Identifiers. Names are human-friendly but notoriously ambiguous, so Identifiers are a safer way of representing Topics uniquely. If a Topic Map contains contributions from many different systems, there is no guarantee that names or even identifiers will be used in a mutually compatible manner. However, Topic Maps define the concept of Scope, which can be used to indicate that material derives from a specified source.