User blog comment:King2218/BAL Notation Part 3/@comment-10429372-20140216140811/@comment-24509095-20140216161413

Well, I was thinking of that before I made that rule in Part 2 and I thought "Hey, why not use it as the number of up-arrows! It would still be correct when c = 1 anyway!". That was exactly what was going on in my head except in another language.