This identifies which EMIX frame-size-mix profile a throughput result row was measured against, and is only meaningful when the companion FrameSize field reads 0; otherwise FrameSize alone identifies a single fixed test frame size. An admin uses this to know that a given throughput number represents performance across a realistic blended traffic profile rather than a single artificial frame size, which is important because carriers often care more about mixed-traffic throughput than single-size worst case. For example, a result row with EmixSequenceId = 5 and FrameSize = 0 tells the engineer this throughput figure reflects EMIX profile 5's blended frame-size traffic, not a 64-byte or 1518-byte-only test.