UML23 — Guard of activity edge should be optional

The standard specifies the guard of an activity edge like this:

guard : ValueSpecification [1..1] = true

Hence it is required that every activity edge has a guard. This should be changed to [0..1] to make the guard optional.
The standard should also say that if a guard is not present it means the same as a "true" guard.

Note that the guard of a state machine transition is optional, so this change will make things more consistent

This issue has already been resolved by, or no longer applies to, the UML 2.5 Beta 1 specification.
Disposition: Closed - No Change