[Persistence-sig] terminology for entity-type

[Donnal Walter]

Having never been a DBA, sometimes I have trouble coming up with
accurate terminolgy for things that I have implemented. I thought I
might take advantage of these lists and ask what may be a naive
question, but any advice would be much appreciated.

If one has a collection (set) of data-entities, each of which is of
the same class, what do you call that class relative to the data
collection? For example, let's say that we have a set of medication
orders (named, say, MedList, even though it is not a true list),
with every item of the set being an instance of the class MedOrder.
I'd like to say that the class MedOrder is the _______ of the set
MedList. I have used the word *domain* ("MedOrder is the domain of
MedList"), but in the little reading that I have done, "domain"
seems to be related to a column rather than to a row. Likewise for
"extent", although I'm still not sure I understand extents.

Thanks,

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Donnal Walter
Arkansas Children's Hospital