[in, unique, size_is(cbAnchor)] A byte array that represents an enumeration anchor, such as a timestamp. Changes that occurred since this anchor are enumerated. If the anchor is null, the provider should enumerate all items in the store.
cbAnchor
[in] Specifies the number of bytes in pAnchor. Returns the number of bytes required to retrieve the ID when pAnchor is too small, or returns the number of bytes written.