An object is a container for a set of values that are stored together or passed together as a set. An object often corresponds to a real-life entity, such as a patient, a patient diagnosis, a transaction, and so on.
Defines registered objects. You can create these objects but you cannot save them. Registered objects are useful for carrying sets of related values that do not need to be stored.
Defines persistent objects. You can create and save these objects.
A persistent class is automatically projected to a table that you can access via InterSystems SQL.
Defines serial objects. A serial class is meant for use as a property of another object. You can create and delete these objects, but you cannot save them or open them independently of the object that contains them.
When contained in persistent objects, these objects have an automatic projection to SQL.