UMLR — Message arguments should not be contained in a message

Figure 14.4 - Messages in the spec depicts that arguments of a message are contained in that message. This containmentship is not necessary and in many cases counterproductive.

The containment prevents ValueSpecifications for being reused in multiple messages. Instead, the very same ValueSpecification must be created in each message.

Since ValueSpecification is a PackageableElement, there is no problem in making the association between Message and ValueSpecification a non-containment association.