The types are average, top, bottom, min, max, peak to peak, amplitude, pulse duration, period and frequency. top and bottom are the means of the upper and lower halves, which is why a unit sine reads 0.637 (2/π) rather than 1.

The on-plot marks come in two kinds and the mix is the reading: a level mark is a ruler at a value, a time mark is a marker at a position. An average draws one level mark; a max draws a level mark and a time mark at the first sample that reached it.

Marks cannot be dragged. A measurement mark says what the measurement measured, so it is created unselectable — as is the trigger marker.

A pass is throttled to a cadence rather than run every frame, so a ruler over a live view is stepped. The number and the ruler come from the same pass, so they always agree.

An invalid pass keeps its level marks and drops its time marks. A level is a property of the signal and outlives the window; a position inside the window does not. That is what stops the rulers blinking off at a mode change.

A crossing is counted with hysteresis, not on a bare level: the thresholds are a tenth of the window's peak to peak either side of the share, and an edge is counted only once the signal has passed the far one. Period, frequency and pulse duration all depend on it. The mid level is exactly where a waveform moves fastest, so any interferer faster than the fundamental recrosses a single level several times per real crossing — a 5 Hz sine with a 500 Hz tone at a tenth of the amplitude reads 39 Hz without the band and 5 Hz with it. The band holds to an interferer a third of the waveform's own size.

The band is clamped to stay inside the data, which is what keeps a threshold set near an extreme usable: a fixed band there would sit above every sample and the measurement would read nothing. A share near an extreme still leaves the band little room, so it rejects less — which is one reason period and frequency offer no share to set.

A window with too few crossings reads invalid / -- rather than a plausible invented number. Frequency over a window holding one edge is the usual case.

frequency is reported in Hz and period/pulse duration in seconds; every other type carries the channel's own unit. A value is written with a metric prefix so its digits sit in 1..999 — 636.62 mV, not 0.64 V — including when the stream declares no unit at all, which is always the case for a math channel: there the prefix goes tight against the number (636.62m), since two decimals of an unprefixed small value is 0.00.

Cost is bounded by reading the summary pyramid the producer already maintains, not the raw window. The values are still exact: a bucket's sum is a sum.

Statistics adds a second line to every measurement showing n, the mean, the standard deviation and the range. Each observation is one recompute of the pane, so n counts windows measured, not samples — a mean frequency over many windows is what that claims to be. Reset clears every accumulator and starts fresh. A change of display window, a CONFIG or a measurement edit also resets; a pause, a resume, a zoom, a pan and the toggle itself do not, so turning the line off to read the plot and back on again keeps the history.