How can a woman accurately determine the end of her menstrual period and the beginning of ritual purity (ṭahāra), especially with the presence of yellowish discharges after the cessation of blood, and her question as to whether the discharge of "white clots" is an indicator of purity?

The dryness, which is one of the two signs of purity, is ascertained when a woman inserts a piece of cloth into her private parts and it comes out clean, free of blood or anything similar. She then performs ghusl, and the rulings pertaining to a pure woman apply to her. If the cloth comes out stained with blood, yellowness (ṣufra), or brownish discharge (kudra), then menstruation has not yet ceased. As for the white discharge (qaṣṣah), it is well-known to women.