The purpose of the IOGP S-731 specification documents is to define a minimum common set of requirements for the procurement of operator and mounting kits for subsea pipeline valves and manifold valves in accordance with API 6DSSX, first edition, published March 2021, Operator and Mounting Kits for Subsea Pipeline Valves, for application in the petroleum and natural gas industries. The IOGP S-731 specification documents follow a common structure comprising a specification, also known as a technical requirements specification (TRS), a procurement data sheet (PDS), an information requirements specification (IRS) and a quality requirements specification (QRS). These four specification documents, together with the purchase order, define the overall technical specification for procurement.