UML22 — Property defines an association "datatype" which is redundant

Property defines an association "datatype". This association is redundant for the following reasons: A DataType is a kind of classifier, so saying that a property can be owned by a DataType adds nothing new. (ii) as feature, one can navigate from the property to the featuringClassifier, and so the navigability to an owning data type is already given. Moreover, an association to a data type would be incorrect if the property would otherwise be owned by a different Classifier. Moreover, if this property is owned by a classifier, there is no guarantee that the datatype association references the same DataType. There are no consistency constraints. Anyway, this association is redundant, can possibly lead to inconsistent models, and should be deleted. The last sentence on p.92 "A property may be owned by and in the namespace of a datatype." is correct even if the association is deleted. However, this sentence adds no new information either and is best deleted also.

see pages 14 - 17 of ptc/2011-01-19