Vertiefende C-Techniken > Schnittstellen > ISO 10303 (STEP) > Die Beschreibungssprache Express > Notation  

EXPRESS: ENTITY

• repräsentiert eine Klasse von Objekten, welche gemeinsame Eigenschaften haben.
• ist definiert durch seine Attribute und lokale Zwangsbedingungen.
• Beziehungen zwischen Entities werden gebildet durch Attribute.

ENTITY point;
            x:       REAL;
            y:       REAL;
            z:       OPTIONAL REAL;
END_ENTITY;

                      ENTITY CIRCLE;
                                   center_point:    point;
                                   radius:              REAL;
                      DRIVE
                                   area:                 REAL :=PI*radius**2;
                      END_ENTITY;
ENTITY vehicle
            ABSTRACT SUPERTYPE OF (car, truck, bus);
            licence_plate:                 STRING;
            number_of_wheels:       INTEGER;
UNIQUE
            licence_plate;
INVERSE
            versions: set [1:?] of product_version for of_product;
END_ENTITY;

                      ENTITY car
                                   SUBTYPE OF (vehicle)
                                   SUPERTYPE OF (limousine,station_wagon)
                      WHERE
                                   WR1: self.number_of_wheels :=: 4;
                      END_ENTITY;

ENTITY product_version;
             of_product:        vehicle;
             version:             INTEGER;
END_ENTITY;