Property

A decoratable element that represents either an attribute of a class or one end of a relation. For example, the attribute age of Person, or the ends of the binary relation studies in connecting Student and University.

Property	Type	Description
`type`	`"Property"`	Discriminator.
`propertyType`	`id` or `null`	The classifier instantiated by the values assigned to the property.
`cardinality`	`string` or `null`	The cardinality, e.g. `"1"`, `"0..*"`, `"1..5"`.
`aggregationKind`	`enum` or `null`	For relation ends, whether the end is a whole in a parthood relation: `"COMPOSITE"`, `"SHARED"`, or `"NONE"` (see Aggregation Kind). `null` is interpreted as `"NONE"`.
`isOrdered`	`boolean` or `null`	Whether the order of the property's assignments is meaningful (only relevant when the maximum cardinality exceeds one).
`isReadOnly`	`boolean` or `null`	Whether the property's assignments are immutable.
`subsettedProperties`	`id[]`	Properties (relation ends) that this property subsets.
`redefinedProperties`	`id[]`	Properties (relation ends) that this property redefines.

Property also carries the properties of Decoratable (stereotype, isDerived) and the properties common to all model elements.

By convention, cardinality matches ^\d+(\.\.(\d+|\*))?$ — a lower bound, optionally followed by .. and an upper bound (* denotes unbounded). The pattern is not enforced, so free-form ranges such as a..b are also accepted.

The example below is the attribute age, of type Integer with cardinality 1, held by the class Person — shown as the property compartment of the class box.

{
  "type": "Property",
  "id": "prop_age",
  "name": { "en": "age" },
  "stereotype": null,
  "isDerived": false,
  "propertyType": "class_integer",
  "cardinality": "1",
  "aggregationKind": null,
  "isOrdered": false,
  "isReadOnly": false,
  "subsettedProperties": [],
  "redefinedProperties": [],
  "customProperties": null,
  "created": "2024-09-04",
  "modified": null,
  "alternativeNames": [],
  "description": null,
  "editorialNotes": [],
  "creators": [],
  "contributors": []
}

Subsetting and redefinition

A relation end can refine an end inherited from a more general relation, in two ways:

Subsetting (subsettedProperties) — the values of this end are always a subset of the values of the end it subsets. In UML this is annotated {subsets parent}.
Redefinition (redefinedProperties) — this end replaces the end it redefines in the context of the specialized classifier, typically tightening its cardinality or retyping it. In UML this is annotated {redefines parent}.

Suppose a general relation parenthood connects Person to Person through an end end_parent (cardinality 0..2). A specialized relation motherhood between Person and Woman subsets that end — every mother is one of the parents — while narrowing the cardinality to 0..1:

{
  "type": "Property",
  "id": "end_mother",
  "name": { "en": "mother" },
  "stereotype": null,
  "isDerived": false,
  "propertyType": "class_woman",
  "cardinality": "0..1",
  "aggregationKind": null,
  "isOrdered": false,
  "isReadOnly": false,
  "subsettedProperties": ["end_parent"],
  "redefinedProperties": [],
  "customProperties": null,
  "created": "2024-09-04",
  "modified": null,
  "alternativeNames": [],
  "description": null,
  "editorialNotes": [],
  "creators": [],
  "contributors": []
}

An end that instead redefines end_parent — for example on a relation specialized for Orphan, forcing the parent cardinality to 0 — lists it in redefinedProperties:

{
  "type": "Property",
  "id": "end_orphan_parent",
  "name": null,
  "stereotype": null,
  "isDerived": false,
  "propertyType": "class_person",
  "cardinality": "0",
  "aggregationKind": null,
  "isOrdered": false,
  "isReadOnly": false,
  "subsettedProperties": [],
  "redefinedProperties": ["end_parent"],
  "customProperties": null,
  "created": "2024-09-04",
  "modified": null,
  "alternativeNames": [],
  "description": null,
  "editorialNotes": [],
  "creators": [],
  "contributors": []
}

Subsetting and redefinition​

Subsetting and redefinition