SYSML11 — DistributedProperty

On p.46 under 8.3.2.4 DistributedProperty it is stated that: '[1] The DistributedProperty stereotype may be applied only to properties of classifiers stereotyped by Block or ValueType.' It does not however state whether a DistributedProperty [Property] may only be applied to a value property (a "block property" typed by a ValueType or DataType) or other Property variations. All examples of the application of DistributedProperty show it applied to a value property. This has implications for sorting into block compartments in BDDs; if a DistributedProperty [Property] may only be applied to a value property then it will always be sorted into the 'values' compartment. It also has implications for aggregation; since a value property must have AggregationKind 'composite', a DistributedProperty will also have AggregationKind 'composite'.

As the issue states, examples of DistributedProperty are shown only for ValueType. Since all details of a probability distribution are left to a user-defined subtype of the DistributedProperty stereotype, however, such a stereotype could be applied to a stereotype typed by a block, such as a part or reference property. Such a stereotype could be defined, for example, to express probabilities of different cases of the block instances referenced by the property. For example, a distribution on the expected number of occurrences could be specified for a property with multiplicity greather than one.
By not restricting the kind of property to which the DistributedProperty may be applied, the current text does not limit its application. A statement limiting it to a value property would contradict the lack of restriction intended by the current stereotype. The constraint does not refer to the type of the property itself but to the Block or ValueType which must own the property.
The issue further states the implications that properties with a DistributedProperty stereotype could appear in different compartments or could have different values of AggregationKind. All these implications flow naturally from the lack of any restriction on the kind of property to which the stereotype can be applied.
The Blocks chapter currently lacks any reference to Annex C.5, Distribution Extensions. Section 8.3.2.4 is the natural place in the Blocks chapter where such a reference could be added. This reference can also indicate that the annex defines distributions only on value properties, without suggesting that DistributedProperty stereotypes are necessarily limited to value properties. Such usage is currently the main expected use of DistributedProperty, but there is no need to restrict it from other possible uses. Moreover, it relies only on standard stereotype extension mechanisms, with no custom notation, so all its implications are those which flow naturally from an independent stereotype.