This identifies which EMIX frame-size-mix profile the latency results in this row were measured against, meaningful only when the companion FrameSize field reads 0, in which case FrameSize alone identifies a single fixed test frame size. An admin uses this to determine whether a latency figure represents realistic mixed-traffic conditions rather than an artificial single-size test, which matters since latency under mixed traffic can be worse due to head-of-line blocking from larger frames ahead of smaller ones. For example, a latency spike appearing only under cienaCesBenchmarkGenTestSessionLatencyResultsEmixSequenceId = 4 and not under any single fixed frame size would point to a queuing interaction specific to mixed-size traffic.