What are the categories of sexual intercourse (watu'a) recognized in law?

Primary text

Sexual intercourse is categorized into three types: lawful (mubah), intercourse under suspicion (shubhah), and absolutely forbidden (haram mahd). Lawful intercourse occurs within a valid marriage (nikah sahih) or legal ownership (milk yamin). By consensus, lawful intercourse establishes the prohibition of affinity (tahrim al-musaharah). Intercourse under suspicion occurs in a void marriage (nikah fasid), void purchase, or when a man has intercourse with a woman believing her to be his wife or slave, or with a shared female slave. This type also establishes the prohibition of affinity by consensus, similar to lawful intercourse.