What the source calls a rotation zone
A rotation zone appears when price has interacted with the same area from both sides. In the source example, an area first acts as resistance, price breaks through it, and a later extremum forms nearby as support. The overlap of those two structural references becomes the rotation zone.
A level can become a zone
If the interaction occurs almost point-for-point, the source treats it as a rotation level. If the two structural references overlap across a wider area, it becomes a rotation zone.
The physical role is still support or resistance
The lesson is clear that rotation is not a separate market force. Operationally, the area still functions as support or resistance; the term describes the way the structure was formed — price recognized the area from both sides.
Avoid heavily churned historical zones
The source rejects old candidate rotation zones when price spent too much time cutting repeatedly through the area and reactions were weak. In that case, a cleaner local level may be more useful than preserving a visually attractive but structurally noisy zone.
A rotation-zone detector should include a churn filter. Overlap alone is not enough.
A formalized detector
Use the same logic across timeframes
The source treats rotation zones as a broadly reusable structure rather than something limited to one timeframe. For software, the threshold for “nearby” should therefore be volatility- or timeframe-aware rather than a fixed point distance.