Caput is a Latin term that in anatomy means head, far end, the top.
In legal terms, the term designates the initial part, title or heading of the article of law or regulation. When the article includes paragraphs (§), items or lines, it is a way of referring only to the main idea of the article, isolating the other elements that constitute it.
In the example below, taken from the Brazilian Penal Code, the caput of article 138 is only the initial sentence "Slander someone, falsely accusing him of a fact defined as a crime":
Art. 138 - Slander someone, falsely imputing to him a fact defined as a crime:
Penalty - detention, from 6 (six) months to 2 (two) years, and fine.
§ 1 - The same penalty is incurred by anyone who, knowing the attribution to be false, propagates or discloses it.
§ 2 - Slander against the dead is punishable.
exception of truth
§ 3 - Proof of the truth is admitted, except:
I - if, constituting the imputed fact a crime of private action, the offended party was not convicted by an unappealable sentence;
II - if the fact is attributed to any of the persons indicated in paragraph I of art. 141;
III - if of the alleged crime, despite a public action, the offended party was acquitted by an unappealable sentence.