The interface layer creates the user's view of the system and is very important in gearing the interaction. Full details of the interface design and implementation are presented in the following chapter.
Interface objects are defined in terms of lower-level ``widgets'' for an X-Windows environment. The interface was built using the X-Windows toolkit TK. It contains both display objects (e.g. for documents, hitlists, extracted term lists etc.) and control objects such as buttons.
An interpreted scripting language (TCL) is used to manage the TK widgets, respond to user-initiated events, and communicate with the query layer via the supplied command language.