Element Metadata

Every OntoUML element carries metadata, regardless of what kind of element it is. This page gathers that shared metadata into three groups and explains how to use each property. The formal definitions live with the abstract types that introduce them — OntoumlElement, NamedElement, and ModelElement — which this page cross-links.

Identity

Every element is an OntoumlElement and therefore carries three identity properties. See Identity properties for the formal definition.

Property	Type	Description
id	id	A non-empty string that uniquely identifies the element within the ontology.
created	pointInTime	When the element was created.
modified	pointInTime or null	When the element was last modified, or null if never modified.

The id must be unique within the ontology, because ids are how elements reference one another instead of being physically nested. The id is also the basis of the model's FAIR identifiers: when the enclosing Project declares a namespace, appending an element's id to that base URI yields a globally unique, resolvable identifier — a FAIR Digital Object. Choosing stable, meaningful ids therefore pays off well beyond the local document.

created and modified use the pointInTime type, which accepts several levels of precision (from a year down to a full timestamp). Use modified to record provenance over time; set it to null when the element has not changed since creation.

Descriptive

Named elements — projects, diagrams, and model elements — additionally carry descriptive metadata from NamedElement. See Descriptive properties for the formal definition.

Property	Type	Description
name	languageString or null	The name of the element.
alternativeNames	languageString[]	Synonyms or alternatives to the main name (not translations).
description	languageString or null	A free-text account of the element.
editorialNotes	languageString[]	Notes about the development process; not to be confused with description.
creators	resource[]	Agents who contributed to creating the element.
contributors	resource[]	Agents who contributed to developing the element.

How to use each:

• name — the primary label. Because it is a languageString, one name can be given in several languages (e.g. { "en": "Person", "pt-BR": "Pessoa" }).
• alternativeNames — synonyms or alternative labels for the same concept in the same language (e.g. "Human" alongside "Person"). These are not translations — translations belong inside the languageString of name as additional language keys.
• description — a human-facing, free-text account of what the element means. This is the text intended for readers of the model.
• editorialNotes — notes about the modeling process (open questions, decisions still to be made, review remarks). Keep these separate from description: editorial notes are for modelers, not for end users of the ontology.
• creators and contributors — the agents behind the element, given as resource references (a name plus a URI), so an author can be linked to an ORCID, a homepage, or another identifier. Use creators for those principally responsible and contributors for others who helped.

All text-bearing descriptive fields use the languageString type, so every label and account can be multilingual.

Custom

Model elements also carry a slot for tool- and domain-specific extensions, introduced by ModelElement.

Property	Type	Description
customProperties	object or null	UML tagged values — arbitrary key-value pairs for extensions not covered by the standard schema.

customProperties is the schema's equivalent of UML tagged values. Use it to attach tool-specific settings or domain-specific attributes that the standard metadata does not capture. Set it to null when there are none. Because these values are outside the controlled part of the schema, prefer the standard metadata properties whenever one fits — reserve customProperties for genuine extensions.

Every property is required

Like all OntoUML properties, every metadata property above is required. A property that carries no information is still written out explicitly: a nullable single value as null, and a collection as an empty array []. There are no optional metadata fields.