 However, all of the control elements in an SIS are dedicated solely to the proper functioning of the SIS.The specific control functions performed by an SIS are called "Safety Instrumented Functions" (SIF).They are implemented as part of an overall risk reduction strategy which is intended to eliminate the likelihood of a previously identified SH&E event that could range from minor equipment damage up to an event involving an uncontrolled catastrophic release of energy and/or materials.