The first part of a subsystem focuses on the presentation and the navigation model. In Netsilon, the concept of dynamic presentation and navigation is based on web elements linked together by decision centers. Decision centers are used as points of variation that dynamically construct the appearance of the page or select a target page according to business rules.

The hierarchy of the web elements follows the structure of the documents in the folder htdocs on disk. A web element can be a web folder that contains other web elements, a web file associated to a real file on disk or a zone, or a polymorphic zone, that is an abstract element whose representation is determined at execution time. Zones have no associated files under htdocs.