Is brown discharge during menstruation considered menstrual blood or irregular bleeding?

"Brownish or yellowish discharge is not considered anything (i.e., menstruation) if a woman sees it after purification. The hadith, by its implication, indicates that it is menstruation if it occurs during the menstrual period. So, if a woman sees it before menstruation and it is connected to it along with its pains, then she is menstruating. But if she sees it after purification, then it only invalidates ablution."