BPMN2 — How to reference particular instances of Data Objects that are Collections

How can one address (in an <assignment>, for example) a particular instance of a multi-instance data object, i.e. a data object with attribute isCollection value set to "true"?

It is unclear why the ioSpecification must be defined with isCollection=true to result in multi-instance execution of the task. Why isn't it sufficient to refer (via the dataInputAssociation/sourceRef element) to a multi-instance data object to trigger multi-instance exection of the task. Is the attribute isCollection needed as attribute of dataInput and dataOutput at all? [Multi Instance Tasks controlled by loopDataInput (Section 10.2.8)]

I assume that defining a data object with isCollection=false based on an itemDefinition with isCollection=true is not allowed, correct? But the reverse is allowed as shown in the document. The question is why supporting isCollection as attribute of an item definition at all; supporting isCollection with elements using the item definition would suffice. [Item Definition as multi-instance (Section 8.3.12)]

A corresponding document (BPMN Script invocation.DOCX) with more background has been sent to Tammo van Lessen.

Section 8.3.12 properly describes the behaviour in the case the data object is a collection.
Disposition: Closed, No Change