The gap between a fast and a slow EMA, and how that gap changes.
The MACD line is EMA(12) minus EMA(26). The signal line is a 9-period EMA of that. The histogram is the difference between the two.
When the histogram crosses zero, the MACD line crosses its signal line: the same event, drawn differently.
Worked out by the same code the builder uses, on stored daily candles. Move a setting and the line moves with it. This is what happened, not what will happen.
Entry: MACD histogram crosses above 0.
MACD above zero simply means the fast EMA is above the slow one. If you already have an EMA gate, MACD often adds nothing new.
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