How to Draw Nassi-Shneiderman Diagrams What are Nassi-Shneiderman Diagrams? Nassi-Shneiderman (NS) diagrams (developed by Ike Nassi and Ben Shneiderman) illustrate algorithms and program functions as a flowchart. The main purpose of a Nassi-Shneiderman diagram is to create a logical structure (a blueprint) for the program. A Nassi-Shneiderman diagram Nassi-Shneiderman Notations Process A process describes a program function as pseudocode. You can stack processes on top of each other to illustrate a sequence. Parallel Process Place processes that are executed at the same time inside a trapezium created by drawing two diagonal lines in the upper and lower border of the table. Loops Use loop notations when processes are repeated until a certain condition is met. Decision The selection symbol is a rectangle divided into three parts by diagonal lines. Write the condition or decision in the uppermost triangle and place the two possible outcomes on either side of the decision. The two outcomes don't need to be the same size. Case statement List multiple cases next to each other in a table format.