Civil Code (Cap. 16), article 791

791. (1) The proximity of relationship is established by the number of generations. (2) Each generation forms a degree. (3) The series of degrees forms the line. Direct line.792. (1) The series of degrees bet ween persons descending the one from the other is called the direct line. Collateral line.(2) The series of degrees between persons descending not the one from the other, but from a common ancestor, is called the collateral line. Direct line may be descending or ascending.