1. 12345678 NOVETO(1) VETO(2) NOVETO(3) VETO(4) NOVETO(5) 3T + Δt fixed decision latency T T LPD latency is fixed = VETO or NOVETO messages arrive with the same fixed delay relative to the pulse being VETOd or NOVETOd, respectively. In the diagram above the fixed delay is 3T + Δt. For LPD the message content can be: a 4.5 MHz yes/no (e.g. 1 = accept, 0 = reject) clock, or the 100 MHz message (3 bit command, 12 bit bunch #, 4 bit reserve) Observations: For 100 MHz messages, the bunch # runs from 1 to bunches-in-train in steps of 1. For 100 MHz messages a given bunch # will be received only once. This scheme is compliant with the 22-Sep-2009 note.

2. 101102103104105106107108 NOVETO(104)NOVETO(105) VETO(104)VETO(101) NOVETO(108) T 6T + Δt 3T + Δt ΔtΔt AGIPD or DSSC latency has variable and fixed components = VETO messages arrive with unspecified delay (nT + Δt) relative to the pulse being VETOd, but NOVETO messages arrive with a fixed delay relative to the current pulse. In the diagram above the fixed delay is Δt. For AGIPD and DSSC the message content can only be: the 100 MHz message (3 bit command, 12 bit bunch #, 4 bit reserve) Observations: received bunch #s do NOT run from 1 to bunches-in-train in steps of 1. a given bunch # can be received twice (NOVETO + VETO) or once (NOVETO) the order of NOVETOs increases the order of VETOs is random (e.g. 104 before 101) T This scheme is compliant with the 22-Sep-2009 note.

3. 101102103104105106107108 NOVETO(104)NOVETO(105) VETO(104)VETO(101) NOVETO(5) T T NOVETO(106)NOVETO(107) x y ΔtΔt What AGIPD seemed to be saying at the 18-Feb-2009 meeting = VETO messages arrive with unspecified delay relative to the pulse being VETOd, but NOVETO messages arrive with a fixed delay relative to the current pulse. In the diagram above the fixed delay is Δt. Message content can only be: the 100 MHz message (3 bit command, 12 bit bunch #, 4 bit reserve) Observations: the bunch # does NOT run from 1 to bunches-in-train in steps of 1. there is NO bunch # ordering in VETO messages (e.g. 101 is later than 104 above) more than one decision can arrive in a give T period. This scheme is NOT (see pipelining) compliant with the 22-Sep-2009 note.