This reports the Maximum Inter-Frame Delay Variation observed during a completed delay-measurement test, in microseconds, the worst single frame-to-frame delay difference seen, distinct from the average IFDV figure reported alongside it. An admin watches this for a single severe delay-variation event between consecutive test frames, which can matter for real-time codecs that rely on smooth, evenly-spaced packet arrival even when overall average jitter looks fine. For example, an average IFDV that looks acceptable but a maximum IFDV spiking far above it would indicate an isolated event, like a brief queuing burst, that momentarily disrupted otherwise smooth frame spacing.