The original system called SignWriting was a system of stick figures showing the human body with arms and sometimes legs as it was created from Dance Writing which showed full body movement. SignWriting as now developed shows the minimum information necessary (the hands only, for example) arranged to show multiple positions in a cluster that is visually "stacked" to be an encapsulated "movement" showing both the beginning and ending positions in a vertical cell (like a filmstrip). With the German version there may be multiple mouth positions that are stacked across to show that a series of mouth movements happens at the same time as the change in hand positions.
Unlike writing sound where one sound follows another, in sign languages many actions may be happening simultaneously so that "stacking" all the symbols together becomes the natural way to show that "A and B" are happening together, not "A, then B".
On a linguistic level, it is the difference between "S" and "Z". The tongue and teeth are both in the same position but the "Z" simultaneously has the vocal cords engaged so that the "Z" is a "S" stacked with a vocal buzz.
Hey Valerie and everybody :)
Thanks again for all your detailed great answers, Valerie!!
I just struggled once while reading an explanation around the SignWriting Newspaper.
You wrote ...
Through writing articles in ASL, the Deaf writers learned what they needed to write ASL, and this experience lead to their request for writing Expressively, for writing in vertical columns, and for writing in stacked clusters instead of using stick figures…
Could you please explain what the last one means: writing in stacked clusters instead of using stick figures?