[Odrl-version2] Still not sure about constraints on duties

[Vicky Weissman]

Hi Renato,

If I understood your response correctly, then the following two statements
are equivalent.  

Party=Alice
Perm=Download
Asset=F
Duty=d
Duty.Constraint=c

Party=Alice
Perm=Download
Asset=F
Duty=d
Constraint=c

Is this right?  If so, why allow duties to have constraints at all?

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Again, if I understood correctly, then

Party=Alice
Perm=Download
Asset=F
Duty=Pay[amt=5]
Duty.Constraint=Date[before30June06]

says that Alice may download F if she has paid 5 and the current date is
before June 30, 2006.  So the encoding does not match the example I gave;
namely, Alice may download F (now) if she pays 5 dollars at the end of the
month.  Examples of similar policies in real life include credit card
policies (you can buy what you want but are obligated; that is, have a duty,
to pay a certain percentage of your balance at the end of the month) and
traditional library policies (you can check out a book but are obligated to
return it within 2 weeks).  

I could understand if ODRL was not interested in capturing such policies but
then having a construct called a "duty" seems odd.   

---------------
Finally, is it true that duties can only require some party to make a
payment, or could a duty require other types of actions such as attribution
being given?  (Note: if a duty can only discuss a payment, then duties are
less expressive than requirements as defined in v1.0, although maybe
requirements in v1.0 can be captured by constraints in v2.0.)

Thanks,
Vicky

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