The vertical lines between blobs within a role are more than just ways of connecting the blobs. They represent states which the role can be in. Our understanding of a RAD is greatly enhanced if we see lines as states rather than just ‘flows’ from one action or interaction to another. This will become more and more apparent as we look more carefully at RADs and the way processes work.
Sometimes on a RAD we want to say what state the world is in at a particular part of the process; in other words we want to label the state. We do this by simply putting a little ‘sensing loop’ around the state line and annotating it, as in Figure 2.6. Similarly, in Figure 2.2, the final state of the