The functionality of Human Machine Interface (HMI) software can vary considerably.  Many software packages are HMI clients used with a variety of control products, such as DCSs, PLC, PACs or PC-based data acquisition systems.  In addition to performing visualization functions, many of these HMI client software packag-es are also used for performing monitoring functions, such as alarming, as well as for data storage and printing management reports.  Some of the more sophisticated packages also perform control functions.  ARC considers script language programming to be an inherent function of an HMI client software package, rather than control and programming.