Establishing a fixed menstrual habit (Adah) based on the observed pattern of flow colors across several months?

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When a woman observes a pattern involving black and red flow across several months, the ruling for the third and fifth months, where clear distinction is lacking or the black flow is superseded, depends on establishing her fixed habit (Adah). If the habit is established by two occurrences, she calculates her habit duration based on the third, fourth, and fifth months. If the habit is established only by three occurrences, she calculates her habit from the fifth month, as she has now observed the pattern in three separate months.