Abstract: A meta model may be provided as a global structure providing flexible or customizable options for a specific ontology designed by a system operator. A meta model may include generic structures, such as attributes, attribute categories, and attribute properties. A system operator may configure a set of specific attributes, attribute categories, and synthesis rules within the meta model to define a desired ontology, customizing the system to a specific purpose. A system can receive assertions about points of interest known to the system, and store information about attributes of points of interest based on the specified ontology.