Errata exists for this version of the document.

It is allowed that subtypes override ModellingRules on their InstanceDeclarations. As a general rule for subtyping, constraints shall only be tightened, not loosened. Therefore, it is not allowed to specify on the supertype that an instance shall exist with the name (NamingRule Mandatory) and on the subtype make this optional (NamingRule Optional). Table 20 specifies the allowed changes on the Properties when exchanging the ModellingRules in the subtype.

Table 20 – Rule for ModellingRules Properties when Subtyping

	Value on supertype	Value on subtype
NamingRule	Mandatory	Mandatory
NamingRule	Optional	Mandatory or Optional
NamingRule	Constraint	Constraint