Enumerations

Several places in the schema draw their values from a fixed vocabulary rather than from free text. This chapter documents those enumerated / controlled value sets. They come in two flavours, and the distinction matters for validation.

Closed enumerations

Some value sets are fixed by the schema itself. Only the listed tokens are legal, and a validator rejects anything outside them. There are two:

• Ontological Nature — the values a Class may list in its restrictedTo array, naming the natures its instances may have.
• Aggregation Kind — the values a Property may carry in aggregationKind, marking the whole end of a parthood relation.

Open, standardized vocabularies

The OntoUML stereotypes are different. The schema stores a stereotype as a plain non-empty string (see Decoratable) and does not constrain it to an enumeration. The lists below are therefore the recommended standard vocabulary — drawn from the OntoUML profile — rather than a closed set. Custom stereotypes are allowed, deliberately, so that tools and modelers can extend the notation.

• Class Stereotypes — decorate class elements (kind, role, relator, …).
• Relation Stereotypes — decorate binary and n-ary relations (material, mediation, …).
• Property Stereotypes — decorate property elements (begin, end).

Closed versus open

Ontological Nature and Aggregation Kind are closed enumerations — validators enforce them. The three stereotype lists are open — the schema accepts any non-empty string, and the standard vocabulary exists for interoperability, not enforcement.