UMS schema

A UMS document is a YAML list. Each item is a TypeDefinition: either an entity type or a relationship type.

Type definition

Field	Purpose
Type	Stable name of the domain type.
Labels	One or more labels for an entity type.
Label	Short label for a relationship type, such as LIKES.
PrimaryKey	Ordered list of properties that identify the type.
Properties	Attribute definitions owned by the type.
Relationships	Directed field mappings to other types.
Source, Target	Endpoint types of a relationship type.
RelationshipAnnotation	A readable statement of the relationship type.
Readings	Readings grouped by language.
Facts	Optional example or asserted facts grouped by language.
UniquenessConstraints	Named unique combinations other than the primary key.
IsRelationshipType	true for an association type; false for an entity type.

Properties

Every property has Name and DataType. The implementation classes support Integer, DateTime, TextFixedLength, and TextVariableLength; the model may also express Length, Precision, Constraints, aliases, fact-based names, arrays, readings, and facts.

Use portable types and state constraints explicitly. NOT NULL expresses mandatory participation; UNIQUE expresses a single-property alternate identifier.

- Name: LoginName
  DataType: TextVariableLength
  Length: 100
  Constraints:
    - NOT NULL
    - UNIQUE
  FactTypeReadings:
    - Language: English
      Readings:
        - {Person} has {LoginName}

Relationships

A relationship has a Name, Source, Target, From, and To. From and To are parallel lists: item 1 maps to item 1, item 2 to item 2, and so on. This supports both simple and composite keys.

Embed and Cardinality are optional document-oriented hints. They do not remove the relationship from the canonical model; they state a useful materialisation choice for a document target.

Readings and facts

FactTypeReadings records a model statement in one or more languages. Each entry contains a Language and its Readings. Facts follows the same language-grouping pattern, but contains instance-level statements or example facts.

FactTypeReadings:
  - Language: English
    Readings:
      - {Person} likes {Film}

The repository also contains an earlier JSON Schema and example YAML that use TypeReadings and Readings directly. Treat the language-grouped FactTypeReadings layout as the current documentation convention; align any validator or generator with the layout it consumes.