eu.cdevreeze.tqa.base.relationship
Either an eu.cdevreeze.tqa.base.relationship.ElementLabelRelationship or an eu.cdevreeze.tqa.base.relationship.ElementReferenceRelationship.
Returns the optional gpl:preferredLabel attribute on the underlying arc.
Either an eu.cdevreeze.tqa.base.relationship.ElementLabelRelationship or an eu.cdevreeze.tqa.base.relationship.ElementReferenceRelationship.