UML22 — Section: Action/Activity

In the actions and activities chapters default values for attributes that are typed by ValueSpecifications use primitives for the default value. For example: 12.3.5 ActivityEdge, p. 352 Attribute weight has default value "1". Is that correct? What if the ValueSpecification is not computable or the value isn't typed by an Integer?

Yes, this is correct. ValueSpecifications are used in these cases, because it is often desirable for the given value to be specified in the model as computed.
The default values are to be interpreted as the corresponding LiteralValue for the given value (e.g., a LiteralUnlimitedNatural, in the case of weight). The type of value to which such a ValueSpecification must evaluate (e.g., UnlimitedNatural for weight) is given in the semantics for the construct. If the ValueSpecification is not computable or evaluates to a value of the incorrect type, then the model is ill-formed and has no meaning.
Revised Text:
None.
Disposition: Closed, no change.