EDGE event on continuous values: fires once on the bar where left crosses right (was below/above, now the other side). USE WHEN: price crosses a moving average, indicator crosses a level (e.g. RSI crosses 30), Stochastic K crosses D. DO NOT USE for discrete/categorical refs like supertrend.direction ({-1,+1}) — use 'transition' instead. DO NOT USE when you want every bar the relation holds — use 'compare' for level/state semantics. For named zones inspect builder_discover(action='get', ref='workflow:named_anchor_zone').