Default addressbook before iOS4?

A couple of questions I really hope someone may have the answer to, as I have been pulling my hair out with a related problem and I am REALLY hoping the current solution I have in mind will nail it...

1) Which addressBook would have been used when a contact was created programmatically (before iOS 4 added ABPersonCreateInSource to allow us to specify which addressBook to save to) - can we safely assume it was ALWAYS Local, or could it sometimes be (say) the "Exchange" addressBo开发者_C百科ok?

Also 2) Does a local addressBook always exist (even if its empty) so I will always be able to find it in an ABAddressBookCopyArrayOfAllSources (under iOS4 at least?)

Any info (or opinions, if that's the best you got!) on either of these gratefully received, as information seems very thin on the ground in this area.

Cheers

Peter

Readers, this post has some ongoing conversation between Peter and I on this topic.

Obtaining Specific ABSource from ABAddressBook in iOS 4+

It does seem like the ABAddressBook is sparsely documented and a bit Byzantine.