Add unit-of-count

[riannella]

Add a unit-of-count to the Constraint

See: https://www.w3.org/2016/poe/wiki/Requirements#POE.R.V.03_Add_concept_of_.27unit-of-count.27_to_Duty_Constraint_Vocabulary

[riannella]

The solution to this has a dependency on #62

[riannella]

Then we add "unitOfCount" as a new constraint to the Vocab

[nitmws]

Had a look into the Requirement and the related User Case: this sound more like a "pay-per-what" or more generic "what-triggers-a-payment" issue.

[riannella]

Apart from a payAmount Duty, what else would "unitOfCount" be used for?

[nitmws]

Pondering that use case I feel this unitOfCount is not a part of a constraint but a constraint itself. Why: in first examples this unitOfCount was part of the Payment Amount constraint defining an amount of money. But in fact unitOfCount relates to the Duty action "compensate": a compensation is triggered if a person or device or ... exercises the action of the Persmission.
I think of creating a constraint with a left operand "dutyTrigger - Defines a context for the Action of a Permission. If this context applies the Action of the Duty has to be exercised." And the right operand has to be an entity like "Permission action exercised by a person" or "Permission action exercised by a device".

[riannella]

Add as new Constraint Name

[riannella]

Added to the vocab