> 78 monospace characters I recall 72 being more common. This left room for a few nested quotes (indented each level by >[space]) before needing to reflow the

> 78 monospace characters I recall 72 being more common. This left room for a few nested quotes (indented each level by >[space]) before needing to reflow the text to fit in 78, the 78 coming from back in the days of text terminals 80 characters wide (leaving two for a border or for formatting marks or for other decoration/indicators). Maybe that was a more localised thing (I'm remembering it from guidelines for mailing lists and/or Usenet groups) and a flat 78 character guideline was more usual around the wider internet?