7.3.6-3 Minimize Action-Sequence Errors for Selecting Plant Variables

If a sequence of actions is required to select a component or variable, the HSI should be designed to prevent misordered action-sequence errors.

Additional Information:
When a soft control is used to manipulate multiple plant components or variables, the user may need to select one, perform the control action, and then deselect it before controlling the next. Errors involving misordering the components of an action sequence may occur. If the user fails to deselect the last component or variable (i.e., the one that was previously controlled), the control action may be performed on the wrong one. The HSI may minimize the likelihood of misordered action-sequence errors by minimizing the number of selection steps, reducing sequential constraints on selection steps, and providing feedback for identifying out-of-sequence steps.