{ 1 } - If you believe that you ought to do A, then do A.
{ 2 } - If you want X to do A to you, then do A to X.
{ 3 } - If you believe that X ought to do A in situation S, then believe that anyone else ought to do A in situation S.
{ 4 } - You ought not to steal.

Formal ethical principles are ethical principles expressible using only variables and constants -- where the constants can include logical terms, terms for general psychological attitudes (like "believe," "desire," and "act"), and other fairly abstract notions (like "ought" and "ends-means").

The other three are examples of formal ethical principles.