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 in the development of the WSS.