A message transmitted during the coordination dialogue by an accepting unit to the transferring unit when the former wishes to propose a change to coordination data as contained in a previous current flight plan or estimate message. If the transferring unit wishes to propose a change to the data contained in a Coordination message, a coordination message shall be transmitted to the accepting unit.

Source: ICAO Doc 4444,

proposes changes of conditions in CoordinationAndTransfer
may refer to ControlAreaBoundaryPoint
may refer to TransferOfControlPoint