Comment by leoc

Guy Steele's keynote talk at Dan Friedman's 60th-birthday academic festival, "Dan Friedman--Cool Ideas", gives lots of the background: https://youtu.be/IHP7P_HlcBk?t=2198 . Apparently the format was originally a parody or adaptation of that of an IBM Fortran instruction manual based on Skinnerian programmed-instruction ideas.