## 4 Discussion: Model for G-QMS in SoS
### G-QMS in SoS Model, Key Aspects  
#### 4.4.1 G-QMS Subject to Client Quality Requirements Dictated by a Contract  
In Figure 2, an independent category [8.7] with Si\({}_{\text{Total}}\) = 6.46 was identified for this aspect. In the SoS project, the relationship between the client and the organizations that form the project's G-organization, especially the main contractor responsible for project management, is fundamentally governed by contractual agreements, which are central, binding documents. In SoS projects, this is an extensive series of documents, including thousands of requirements, and encompasses all the project topics and areas, including the quality management requirements. In practice, the G-organization configuration for the project and its structure of responsibilities is determined at the stage of defining the contract requirements. In particular, the quality contractual requirements (including those received from the supervisory bodies) directly affect the G-QMS in SoS configuration, its structure of responsibility, and its contents. Contractual quality management requirements are the client's direct _special requirements_, and typically go beyond the standards requirements, to which the SoS project chief management is obligated under the contract. These requirements have a pivotal validity to assure quality; therefore, they are highly important for all QMS entities within the G-QMS in SoS. To ensure that the quality management aspects of the project are comprehensively and accurately addressed within the contract, it is imperative that relevant quality management bodies are involved right from the initial stages of client engagement. This includes participation in the tendering process and subsequent contract formulation phases. For this purpose, those quality bodies should be identified and defined already during these early stages both by the relevant G-organization bodies, particularly the main contractor, and by the client. As presented in [PERSON] and [PERSON] [2], the research results indicate the growing trend of expanding and deepening of contractual quality requirements within SoS projects. The responsibility for the contract quality requirements primarily lies with the QMS Client entity. However, if it fails to do so, a typically weak G-QMS in SoS will be built, which may lead to a poor project quality level. In the light rail sector, the contract quality requirements were found to be usually poor and insufficient; however, they include a mechanism in purpose to refine and consolidate them. The essence of this practice lies in the refinement and deepening of quality requirements after the contract has been finalized, which involves a collaborative approval mechanism that engages both the QMS Client and the QMS M&C Local\({}_{\text{SoS}_{*}}\). This mechanism is designed to review and approve project documents, which include quality requirements, produced by the main contractor with the signed approval of SoS G-QMS CORE. The G-QMS in Sectors of SoS model is characterized by a mature, impressive G-QMS, which includes advanced internal requirements originating from the G-QMS CORE of the G-QMS of G-Org. of SoS, including the requirements for QMS standard certifications and other relevant standards. However, the G-QMS in SoS foremost is committed to the quality requirements outlined in the contract. In instances where there is a discrepancy between a contractual quality requirement and the internal policies, procedures, or directives of the G-QMS of G-Org. of SoS, the contractual requirement takes precedence. Beyond the direct quality management requirements for the project for which the G-QMS is responsible, the relevant quality bodies participate already in the initial engagement processes with the client to ensure thorough _contract review processes_ for all the contract requirements.