Information taken from openfire_src_3_3_2/src/java/org/jivesoftware/openfire/roster/RosterItem.java
ASK_NONE = -1
The roster item has no pending subscription requests.
ASK_SUBSCRIBE = 0
The roster item has been asked for permission to subscribe to their presence but no response has been received.
ASK_UNSUBSCRIBE = 1
The roster owner has asked to the roster item to unsubscribe from it’s presence but has not received confirmation.
RECV_NONE = -1
There are no subscriptions that have been received but not presented to the user.
RECV_SUBSCRIBE = 1
The server has received a subscribe request, but has not forwarded it to the user.
RECV_UNSUBSCRIBE = 2
The server has received an unsubscribe request, but has not forwarded it to the user.
SUB_REMOVE = -1
Indicates the roster item should be removed.
SUB_NONE = 0
No subscription is established.
SUB_TO = 1
The roster owner has a subscription to the roster item’s presence.
SUB_FROM = 2
The roster item has a subscription to the roster owner’s presence.
SUB_BOTH = 3
The roster item and owner have a mutual subscription.