An D21: Algebraic structure $R = (X, f, g)$ is a ringoid if and only if

(1)	$\forall \, x, y \in X : f(x, y) \in X$ (D20: Enclosed binary operation)
(2)	(2) $\forall \, x, y \in X : g(x, y) \in X$ (D20: Enclosed binary operation)
(3)	$\forall \, x, y, z \in X : g(x, f(y, z)) = f(g(x, y), g(x, z))$ (D555: Left-distributive binary operation)
(4)	$\forall \, x, y, z \in X : g(f(x, y), z) = f(g(x, z), g(y, z))$ (D556: Right-distributive binary operation)