This Technical Specification, part of the IEC 61508 series, covers the general assurance of dependable software used in critical operational-technology (OT) which is running on hardware devices which are specified as part of the OT application. It is particularly aimed at safety-related software which is being developed according to the E/E/PE software functional safety standard IEC 61508‑3; in particular, the development of the software follows a Formal Safety Requirements Specification. Successful use of some or all of the assurance points specified in this document enhances the confidence that a particular piece of safety-related software meets the requirements of the SIL of the safety function which it (partially or fully) implements, and thereby increases the systematic capability of the software.