I had asked where should the arrow face. K. Dianne Stephens (privately), Hans Dybkjær, and Anne LaVin, mentioned that the tail of the arrow would point to the prior step and the head to the next step. Anne LaVin also, suggested to look for that arrow in Robert Lang's article on diagramming.
Thank you for your replies. I looked in Robert's article as you suggested me Anne. So it seems to me there are two versions regarding the direction of this arrow, in one position connects the step before being turned over with the step after it's been turned over, in the other version (in Robert's article) the arrow's direction determines how the model must be turned over (vertically or horizontally). I suppose this is where the beginners' guide that Anne suggested would come in handy : ) Also thank you for explaining me that "diagrammer" is also a person. I was confused since in the web I only found the word diagrammer used to refer to software programs.
