Rubric
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
Directions printed in books of law and in prayer-books, so termed becanse they were originally distinguished by red ink.
— Rubric of a statute. Its title, which was anciently printed in red letters. It serves to show the object of the legislature, and thence affords the means of interpreting the body of the act; hence the phrase, of an argument, "a rubro ad nigrum." Wharton.