A Weapons Systems Specification (WSS) is a list of detailed requirements that are developed by the contractor during the development of a weapons system. It provides more detailed information about the weapon system than the government-provided Initial Capabilities Document (ICD) and Capabilities Development Document (CDD). The WSS is what’s actually used during the development, design, and building of a weapons system by a contractor. It must be traced back to the CDD and ICD for verification and validation. The Program Management Office (PMO) usually provides a Systems Requirements Document (SRD) to the contractor with the Request for Proposal (RFP) to facilitate the development of the WSS.