Reply To: tn for formal proof format
Here's the one my teacher taught me in 1967.
In formal proofs in this volume, the format showing step-numbered "Statements" and "Reasons" in two side-by-side columns has been changed. The braille shows all statements and reasons beginning at the margin and the letter S or R following the step-number.
HTH Barbara Taffet
PS. My teacher was Helen Roberts, the original author of the Intro to Braille Mathematics. I only completed the book after she died prematurely.