User blog comment:Nayuta Ito/Introduction to AAN/@comment-29014792-20160805233152/@comment-25337554-20160808101100

Yes, I am looking at case B3 because {0,1} starts with zero.

Copy the separator to R. Now R is {0,1}.

Replace the PREVIOUS entry before the separator with '0 R 1'.

Now  a(x,y,0{0,1}z) becomes a(x,y,0{0,1}1{0,1}z-1)

Continue the process within R separator

Well, I guess you mean, "change {0,1} as if it were a(x,y,0,1)." Now I think I understand.