In a structured analysis and design method, state models show the modes in a system and usually connect to data flow diagrams using control bars and control flows. In an object-oriented approach a state model is typically used to describe the lifecycle of a complex object. The Harel state model illustrated below has become popular in recent years due to its ability to express concurrency.
Tables are also an effective way of expressing information about states and events as illustrated in 1 state transition table.Tables can be created with the table editor much like filling in cells of a spreadsheet. Tables can be generated automatically from information in a state diagram.
Tables are often combined with data flow diagrams to control when processes are active or to generate output control flows from input control flows.
