Address Book owner

TheREST schema of the Contacts API defines aWindowsLiveID element for the Address Book owner (the/LiveContacts/Owner element in the schema). The minimum number of occurrences of this element is 0 and the maximum number is 1, but so far I only observed the element being present.

As the minimum number of occurrences is 0, when can we expect theWindowsLiveID element not being present?

Thanks.

[587 byte] By [ChrisW] at [2008-2-15]