When is ghusl obligatory after menstruation if its duration extends to twelve days, knowing that the usual period was six or seven days, and when is spotting (kudra) not considered anything?

Discharge (kadira) and yellowish discharge (sufra) are not considered menstruation unless they occur during the customary period or are connected to blood. If a woman sees them during her customary period, they are considered menstruation, and she must refrain from prayer. If the bleeding stops and she sees discharge connected to it, it is also menstruation. Similarly, if it is not connected to it but occurs during her customary period [it is menstruation]. However, if she sees purity (tuhur) and then sees yellowish or discharge outside the customary period, it is not considered menstruation but rather irregular bleeding (istihadha).