ABCD

ABCD detects the simplest harmonic structure from confirmed swing points and projects its completion before price gets there. When alternating swings produce an A-B-C sequence whose C retracement lands inside the valid window, the build draws the legs, a dashed line at the classic AB=CD completion where CD equals AB, and, optionally, dotted lines at the 1.272 and 1.618 extended variants plus a shaded BC extension zone. Completion is declared only when a confirmed swing lands within tolerance of a tracked ratio; the D label reports the matched ratio, full measurements in its tooltip.

How to Trade the ABCD?

• Projection in advance: with A, B and C confirmed, the 1.000 line and the BC zone mark where a reaction is worth evaluating, and agreement between the two upgrades the level.
• D Reached vs Completed: price touching the 1.000 projection is information, not a pattern — completion requires the next confirmed swing to match a tracked ratio.
• Voids: a move beyond point A, an overshoot past the furthest tracked ratio plus tolerance, or a second swing printing after the D candidate removes the structure.

ABCD Settings

• Swing Length (default 10): bars on each side confirming a swing; larger values find bigger, later patterns.
• C Retracement Min (default 0.618): lower bound of the valid C retracement of AB.
• C Retracement Max (default 0.786): upper bound; C may never exceed A.
• Completion Ratio Tolerance (default 0.05): accepted CD-to-AB deviation — 0.95 to 1.05 times AB completes the classic form.
• Extended Variants (1.272 and 1.618) (default on): also project and match the extended completions.
• BC Extension Zone (1.272 to 1.618) (default on): shade the second way of projecting D.
• Style: Leg Line Width (default 2) and Point Labels (A, B, C) (default on); the D label always shows.

Frequently Asked Questions

How does the ABCD relate to five-point patterns like the Crab?

The AB=CD is the engine inside most of them — larger harmonic definitions generally expect an equivalent or extended ABCD finishing at their own D point. A dedicated detector like the Crab adds the X leg and a stricter ratio set; this build isolates the reusable core.

Why did a forming pattern disappear?

It was voided: price broke beyond A, overshot the furthest tracked completion by more than the tolerance, or another swing confirmed after the D candidate. A violated ABCD is dropped, not renegotiated.

Which alerts does the build provide?

Three per side: Forming when C confirms inside the retracement window, D Reached when price first touches the 1.000 projection, and Completed when a confirmed swing matches a tracked ratio.