# Half-Retracement Reversal Detector Half-Retracement Reversal Detector is an indicator on [Vela](https://vela.luxalgo.com/chart), our next-generation charting platform, written in Pine Script®. Detects bullish and bearish 5-0 harmonic patterns from confirmed swings, validating the 1.13-1.618 AB/XA and 1.618-2.24 BC/AB extensions and projecting the D zone from BC's defining 0.50 retracement. A reciprocal AB=CD cross-check, a 0.618 invalidation retracement, point and ratio labels and a target line at C complete the build, with ten alerts. - Indicator in the LuxAlgo Library, by LuxAlgo, published Jun 20, 2026. - Access: free. - Concepts: [5-0](https://www.luxalgo.com/library/concept/5-0/) (primary) - Open on Vela: https://vela.luxalgo.com/chart?pineScriptCodeId=bez9zui4h6mrnu8vce0jyooh - Page: https://www.luxalgo.com/library/indicator/5-0/ **Half-Retracement Reversal Detector** finds the harmonic structure known as the [5-0®](https://www.luxalgo.com/library/concept/5-0/), whose reversal zone sits at a 0.50 retracement of its last leg. Confirmed swings assemble the 0-X-A-B-C sequence: an initial swing into X, an AB leg reaching 1.13–1.618 of XA beyond X, a BC leg stretching 1.618–2.24 of AB, then a D zone projected at BC's 0.50 retracement, the number the pattern is named for. Each structure draws its legs, points and ratios, and boxes the D zone. ## How to Trade with the Half-Retracement Reversal Detector? - **Completion**: price trading into the D zone completes the pattern, the risk-defined entry area. - **Reaction**: a close back in the BC direction while the zone holds, the confirmation read. - **Invalidation / target**: a decisive close through the Invalidation Retracement voids the setup; the dotted line at the C extreme marks the objective. Completions inside the pivot confirmation lag are back-filled; a projection is dropped as stale once price runs beyond C without touching the zone. Like the rest of the [harmonics family](https://www.luxalgo.com/library/family/elliott-harmonics/), it is a reversion structure: trade the measured zone, not a prediction. ## Half-Retracement Reversal Detector Settings - **Swing Length** (default 8): pivot length for the swings forming 0 through C; larger finds larger, rarer structures. - **AB / XA Range** (default 1.13 to 1.618): AB's allowed extension of XA; AB must travel beyond X. - **BC / AB Range** (default 1.618 to 2.24): BC's allowed extension of AB. - **Invalidation Retracement** (default 0.618): the BC retracement whose decisive close invalidates the D zone. - **Reciprocal AB=CD Check** (default on) with **Reciprocal Tolerance %** (default 15): requires the projected CD leg to roughly equal AB. - **Require C Beyond Point 0** (default off): demands BC break the pattern origin before the zone is trusted. - Display toggles: **Point Labels**, **Ratio Labels**, **Target Line** and **Show Swings** (all on by default). ## Frequently Asked Questions ### How does the 5-0 differ from an ABCD? An ABCD is a four-point symmetry pattern, the one the [Measured Move Detector](https://www.luxalgo.com/library/indicator/abcd/) finds, while the 5-0 embeds its reciprocal (a CD leg roughly equal to AB) inside a five-point structure whose opening legs break the prior trend. The build's cross-check makes that an explicit rule. ### Why is the D zone anchored at a 0.50 retracement? Because the precise 50 percent retracement of BC is the pattern's defining measurement, the number in its name. The zone spans from that level to the invalidation retracement, giving the trade a defined floor. ### What makes a projection disappear without completing? Two cases: a newer qualified setup replaces a stale awaiting projection, and price running beyond the C extreme before touching the zone deletes it. Resolved structures stay on the chart. --- Bat®, Crab®, Shark®, AB=CD® and 5-0® are registered trademarks of their owner, used here only to identify the patterns. LuxAlgo's tools are independent implementations and are not affiliated with or endorsed by the trademark owner. ## Related indicators - [Cypher](https://www.luxalgo.com/library/indicator/cypher/) (Elliott & Harmonics): markdown at https://www.luxalgo.com/library/indicator/cypher.md - [Harmonic Pattern Detection](https://www.luxalgo.com/library/indicator/harmonic-pattern-detection/) (Harmonic Patterns): markdown at https://www.luxalgo.com/library/indicator/harmonic-pattern-detection.md - [Measured Move Detector](https://www.luxalgo.com/library/indicator/abcd/) (ABCD): markdown at https://www.luxalgo.com/library/indicator/abcd.md - [Three Drive Pattern Detector](https://www.luxalgo.com/library/indicator/three-drive-pattern-detector/) (Three Drives): markdown at https://www.luxalgo.com/library/indicator/three-drive-pattern-detector.md - [Potential Reversal Zone](https://www.luxalgo.com/library/indicator/potential-reversal-zone/) (Elliott & Harmonics): markdown at https://www.luxalgo.com/library/indicator/potential-reversal-zone.md - [Anti-patterns](https://www.luxalgo.com/library/indicator/anti-patterns/) (Elliott & Harmonics): markdown at https://www.luxalgo.com/library/indicator/anti-patterns.md - [RSI BAMM](https://www.luxalgo.com/library/indicator/rsi-bamm/) (Elliott & Harmonics): markdown at https://www.luxalgo.com/library/indicator/rsi-bamm.md - [Overextension Reversal Detector](https://www.luxalgo.com/library/indicator/shark/) (Shark): markdown at https://www.luxalgo.com/library/indicator/shark.md --- Source: https://www.luxalgo.com/library/indicator/5-0/ (LuxAlgo Library). Free to use with attribution: https://www.luxalgo.com/library/license/