§A property may be marked as the subset of another, as long as every element in the context of the subsetting property conforms to the corresponding element in the context of the subsetted property §The collection of values associated with an instance of the subsetting property must be included in, or the same as, the collection of values associated with an instance of the corresponding subsetted property §The UML2 API and code generator provide support for Java code to enforce these subset constraints