<<< native [ EUnderover False (EIdentifier "BASE") (EIdentifier "under script") (EIdentifier "over script") , ESymbol Rel "=" , EUnder False (EOver False (EIdentifier "BASE") (EIdentifier "over script")) (EIdentifier "under script") ] >>> eqn BASE from {under script} to {over script} = {BASE to {over script}} from {under script}