What is the ruling on menstrual blood that is consistently black in color without variation?

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If the menstrual discharge is uniformly black, such as seeing three days of black blood every month, which then turns red, and the duration does not exceed the maximum limit of menstruation, then the black blood alone constitutes the menses (Hayd). Furthermore, if the black blood does not exceed the maximum duration of menses, the entire flow is considered menses because it is blood capable of being menstrual blood, similar to a case where all the blood is red.