Many activities require a basic vocabulary, shared with other practitioners. Below are some of the graphical symbols most commonly used in A3 development.
Commonly-used PI symbols
Most of the symbols shown below are self-explanatory. The start/begin and stop/end ovals are commonly used in flow-charting, to delimit a diagram. A diagram consists of a series of action steps, usually described in a rectangle, and sometimes in a hexagon if the activity refers to a setup task rather than to a proper process step. These rectangles are usually linked by arrows, to show the actions are in sequence.
Sometimes, one comes to a step where a decision has to be taken, and on the basis of the answer, either of two paths may be taken. This is usually shown as a “decision diamond”, with one arrow going in (from the previous step, and two arrows flowing out into two steps, each on a different exit path.
The “cloud” symbols are not from standard flow-charting, but from a subset of healthcare PI symbols: problems are usually framed in “spiky” clouds, whereas fixes are shown in “fluffy” ones. They are meant to be drawn floating around and next to specific process steps.
Time delays are there to show that certain actions cannot occur for a specific period of time.
The humble connector symbol, linking diagrams on different pages, is very useful in promoting the sectioning off of parts of diagrams, or layering of the same. In engineering, it is common to have a piping diagram, an electrical layout diagram, and an architectural diagram for a given building on different transparencies (mylars), which you overlay. Ditto if you display these on a PC with a CAD tool. Just think, if everything were on the same diagram, the aggregate complexity would be overwhelming. As I said, they can be used in at least two different ways: to compartmentalize parts of a diagram at the same level of abstraction, or to layer diagrams according to varying levels of detail. Therefore, connectors are a great means of promoting simplification and clear thinking, if properly used.