Definition
−Let T be the reference date: [Protection received.Date of original protection value] (T) = [Protection received.Date of original protection value] (T-1)
+Let T be the reference date: IF [Instrument-protection received.Instrument ID] (T) IN [Instrument-protection received.Instrument ID] (T-1) THEN [Protection received.Date of original protection value] (T) = [Protection received.Date of original protection value] (T-1)