What it is
An NR7 day is a session whose high-to-low range is the smallest of the last seven. It is the shortest-term tight-range signal there is. One quiet day follows a week of larger moves. Tight ranges tend to be followed by wide ones, and NR7 is how traders find the day before that happens.
How Breakaway uses it
NR7 fires when the latest bar has the narrowest range of the last seven bars. It counts on the finished day: during the session it keeps the last close's answer. It is a tight-range check and one of the predictive four. Because it is a one-day pattern it flips on and off often. So it matters most when it shows up with the slower tight-range checks, the ATR squeeze and the Bollinger squeeze, and inside a trend.
How to read it
The textbook use is to buy a break above the NR7 bar's high, with a stop below its low. Risk stays small because the bar itself is small. If the break comes on light volume, treat it with suspicion. The best NR7 breaks come with a jump in relative volume.