Some legacy services maintain server-side contact lists, which are sent to the gateway when it logs in to the legacy service on behalf of the user. The gateway MAY initiate adding of the legacy contact list items to the user's Jabber roster. Some existing gateways do this by sending a presence stanza of type "subscribed" from the legacy contact's JID (e.g., <LegacyUser@gateway.jabberserver.com>) to the Jabber user; unfortunately, this behavior violates the presence stanza handling rules specified in RFC 3921. Therefore, a gateway SHOULD instead send the legacy contact list items to the Jabber User via the &xep0144; protocol.
-There are two scenarios for gateway handling of roster groups: either (1) the legacy service does not support groups or (2) the legacy service supports groups.
-If the legacy service does not support categorization of contact list items into groups (equivalent to XMPP roster groups), then a gateway that handles communications with such a legacy service SHOULD enable the user to specify his or her desired roster group for those items by providing a field of "group" in the data form it provides to the user on registration.
-When the gateway sends roster items to the user, it SHOULD then include the specified group.
-However, if the legacy service supports groups, then a gateway that handles communications with such a legacy service SHOULD enable the user to specify his or her desired roster group prefix or suffix for those items by providing fields of both "group" and "groupmodify" in the data form it provides to the user on registration.
-When the gateway sends roster items to the user, it SHOULD then include the group name from the legacy service, prepended or appended with the groupmodify value.
-Some legacy services maintain server-side contact lists, which are sent to the gateway when it logs in to the legacy service on behalf of the user. The gateway MAY initiate adding of the legacy contact list items to the user's Jabber roster. Some existing gateways do this by sending a presence stanza of type "subscribed" from the legacy contact's JID (e.g., <LegacyUser@gateway.jabberserver.com>) to the Jabber user; unfortunately, this behavior violates the presence stanza handling rules specified in RFC 3921. Therefore, a gateway SHOULD instead send the legacy contact list items to the Jabber User via the &xep0144; protocol.
The following business rules apply: