Modeling properties. Properties of concrete concepts are held by the typed class Property. Instances of its type definition class PropertyType (gcType, mtType, and funcType) specify the meaning of properties with their attribute name. The attributes valueType and cardinality restrict the data type and number of hold values. PropertyHolder and PropertyRegistry support the handling and definition of property sets. The PropertyHolder aDnaMol holds the Property gcProp of type gcType; the optional Property of type mtType is not set.