This property relates to open incoming associations only, and can be accessed at any time after the association has been made. For "outgoing" DicomAssociation objects, they are null and 0. For "incoming" DicomAssociation objects such as those created automatically as part of incoming C-STORE (Async), C-FIND of C-GET requests, they relate to the association received. For C-MOVE, they continue to refer to the incoming association even once an outgoing association to carry the images has been established.