PartDefinition

Original XMI declaration. §7.11.1 Parts Overview, printed 58 / PDF 90; §8.3.11.2 PartDefinition, printed 289 / PDF 321

What to understand

• A definition is a classifier; a part usage is a feature in context. They retain different metaclass identities.
• Declaring a nested definition introduces a scoped kind. It does not by itself declare a part usage.
• Properties of this metaclass describe the language definition, rather than arbitrary attributes such as a modeled wheel diameter.

Graphical notation

These are representative, source-checked variants, not an exhaustive notation grammar. The illustrations are original redraws, not official figures.

Part definition node

Context: Definition node in a structural view.

Sharp-corner rectangle with the part def keyword and definition name. Compartment and interconnection contents may extend the basic node.

§8.2.3.11 Parts, printed 209 / PDF 241

Relationships and composition

Usage of a kind: PartUsage

Part usages can use the kind introduced by a part definition.

Condition: Typing is distinct from model ownership; many usages can share the same definition.

§7.11.2, printed 61 / PDF 93

Declared feature: PortUsage

A part definition can declare port usages as features.

Condition: Port definitions determine permitted port typing; the enclosing declaration is not a substitute for that type.

§7.12.2–3, printed 63 / PDF 95

Connected example

Wheel, Axle and Assembly are part definitions. Their port and part declarations specify features; assembly : Assembly is a separate usage of the defined kind.

// Original documentation example. Source-reviewed; not parser-validated.
package AssemblyExample {
    port def Mount;

    part def Wheel {
        port hub : Mount;
    }

    part def Axle {
        port mount : Mount;
    }

    part def Assembly {
        part wheel : Wheel;
        part axle : Axle;
        ref part spare : Wheel[0..1];
        connection link connect axle.mount to wheel.hub;
    }

    part assembly : Assembly;
}

Verification: source-reviewed, not parser-validated or executed. §7.11.2 Part Definitions and Usages, printed 61 / PDF 93

Properties

The explicit-redefinition view contains 82 active declarations, retaining declaration origins and excluding 0 replaced declarations. It deduplicates diamond paths by identity, excludes private inherited fields, and reports unresolved same-name collisions instead of choosing a winner.

These are metamodel property cardinalities and declared defaults. They do not determine the multiplicity or runtime values of a part, port or connection in a user model. Derived values still require their derivation rules. See property rules.

Reconciliation and limits

Seed reconciliation: SelectedFieldsMatch for direct bases, declared property names/types/bounds/derivation/ordering/subsets/redefinitions, constraint names. This checks selected structural fields only; it does not approve the entire seed or all semantics.

• Instance-level composition is governed by usages and their context, rather than by the outline of the definition box.
• Effective property resolution covers explicit inheritance and redefinition identities; it does not evaluate constraint consistency, OCL derivations or executable behavior.

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