The basic format of structured proofs is surprisingly similar to how middle-school math typically teaches students to write proofs, the "two-column proof" struc

The basic format of structured proofs is surprisingly similar to how middle-school math typically teaches students to write proofs, the "two-column proof" structure. A proof is a sequence of numbered statements in the left column, each of which has to be justified by reasons noted in the right column, which are either appeals to a previous numbered statement, or to a named theorem/lemma already introduced in the textbook. Instead of using the second column, Lamport instead writes "PROOF: ..." and gives the justification below each numbered statement, but it otherwise seems quite similar.