OptionalfrequencyOmitted retains evaluation only when a new bar is appended. Explicit policies also observe qualifying updates within a bar. once is spent only by a delivered live event and lasts for this instance's lifetime. Historical loads, replay and settings-only recalculation never deliver.
Stable within the descriptor, e.g. 'cross-up'.
OptionalmessageLonger text for a notification; defaults to title. A function is handed
the same context when judged, so the message can carry the bar's own
numbers: the price it crossed at, the histogram reading, a JSON body for a
webhook. It runs only for a bar when accepted.
Short human label, e.g. 'MACD crossed up'.
A condition the runtime watches, declared by the descriptor rather than wired up by the host: the indicator is the only thing that knows what a crossover of its own columns means.
Evaluated once per bar, for bars that are new since the last evaluation, so adding the indicator to a loaded chart fires nothing for history.