Table 2.

Describing entities, model entities, and real world entities and their order

ISO 11179 descriptive entity	ISO 11179 definition	Notation within the GFO framework	Example: model entity, being an instance of a descriptive entity	Real world entity, modeled by a model entity
metadata object	is an object type, defined by metamodel	metadata type (2)	Classes (1):Object_Class;Characteristic	Categories (2):Object class; Property
metadata item	is an instance of a metadata object	metadata item (1)	Objects (0):Person; Blood Pressure	Categories (1):Person; Blood Pressure
type of application level data	is specified by a metadata item	application level data type (2)	Classes (1):Person; Blood Pressure
real world data	is an instance of application level data type	application level data item (1)	Objects (0):John; Blood Pressure of John	Individuals (0):John; Blood Pressure of John

(x) - entity of order x