Andrew Patterson wrote:
> The ADL spec (section 4.3.3) says that
>
> "with no cardinality, the meaning is that each child object
> constraint of the attribute in question is a possible
> alternative for the value.."
>
> i.e. that this attribute is "single-valued" and the
> types are multiple alternatives.
>
> It then gives an example and says
>
> "here, the cardinality of the value attribute is 1..1
> (the default), which the occurrence of both QUANTITY
> constraints is optional..."
>
> I just wanted to confirm that the selection between
> single-valued and multi-valued is dependant on the
> _absence_ of a cardinality definition, not on whether
> the cardinality is 1..1. So for a single value attribute,
> it is actually illegal to put the "cardinality matches {1..1}"
> in the archetype definition??
>
yes that is correct. To be correct, "cardinality" is a property of
multiply valued attributes, not of single-valued ones. UML and many OO
books make a mess of this, and don't differentiate or even properly
define the meanings of "cardinality", "multiplicity", "optional", ....etc
- thomas
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