In a multi user environment, as user should only sync with the address book on one computer (the one that they use all the time). At no time, should a user log into DayLite from another computer and then do an Address Book sync with that other computer.

DayLite keeps a map of between a DayLite Contact and an Address Book ID on a per user basis. Address Book ID's are unique per computer and thus, many duplicates can be created (and in some cases contacts can be deleted).

It is safe to sync a specific DayLite Contact (using constraint groups) into the Address Book of different DayLite users. So DayLite Contact 'John Doe' can be in User Bill's Address Book on Bill's computer and 'John Doe' can also be in User Mark's Address Book on Mark's computer.