Cross below

Fires on the bar where one series moves from at or above another to below it.

Cross below compares two inputs, a and b. It fires on a bar where a is below b and, on the bar before, a was at or above b. It fires once per crossing, not while a stays below. Both inputs have no default; on this chart both read the close, so they never cross and no markers appear.

How to read it

Markers sit on the candles at each bar where a crosses below b.
In a strategy, bind a to a fast line and b to a slow one, such as a 20-bar and a 50-bar average.
With this chart's inputs both sides are the close, so no markers appear.

What it outputs

Cross below: On only on the bar of a crossing; empty on every other bar.

When it fires

On the bar where a is below b after being at or above it on the bar before. On this chart both inputs are the close, so it never fires.

Pitfalls

A crossing needs a value from both inputs on both bars; a gap in either one skips that crossing.
Two noisy series cross back and forth often; a smoother b cuts the false crossings.