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An ObjectCollection on the other hand is a list of objects. The list of objects is also defined by a Schema and contains an Id and a (translatable) Label. An example of such a list of objects would be invoice items from a CRM. On one invoice, with one recipient, several invoice items appear. The ObjectCollection allows to store several objects of the same type.
MERKENOTE
If you want to allow one recipient in a template, use Objects. If you want to allow multiple recipients (e.g. in a protocol), use an ObjectCollection.
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