Process control relates to the control of the parameters of a process, such as a manufacturing process. The parameters can include duration, temperature, pressure, speed, quantity, and/or direction of motion, for example. In other processes, such as in those performed in the course of using and maintaining information systems, management systems, and the like, the parameters can relate to paper documents or machine-readable media, or to intangible quantities such as units of time or units of money such as a credit limit, or to a result such as can be created by a printer, a visual display module, or an aural signal. Process control systems can be used to help manage production, monitor and maintain equipment, and/or perform business functions such as maintaining inventory records, performing accounting, and tracking sales.