Concept help - Object Class
Set of ideas, abstractions or things in the real world that are identified with explicit boundaries and meaning and whose properties and behaviour follow the same rules ISO/IEC 11179 - Clause 3.2.88
An object class represents a person, organisation, structure or event that is of interest and needs to be described. Examples of object classes include Person, Dwelling and Family.
The union of a specific object class with a specific property creates a data element concept. For example, some of the above mentioned object classes can be combined with an Religious affiliation property to create the data element concepts: Person — religious affiliation and Family — religious affiliation.
Object classes can be specialisations of other object classes. For example, Adult is an age group related specialisation of Person.
Specialisations allow object classes to be grouped and subtyped in a meaningful manner and help users in browsing and locating relevant object classes. In a specialisation tree an object class can only be associated with a single parent object class but may have more than one child object classes. A child object class inherits all characteristics of its parent object class, but a child object class may have unique characteristics.
- Be generic: An object class should apply to the widest group possible. Only make more specific classes, if there are particular attributes only found on the specialisation. e.g. Person, not Australian Citizens
- Use singlar forms: When discusing individuals, use singular terms to ensure unambiguity. For example, a Person can have an age, but a Group of people has an average age.