A public sector agency (Employer) signed a contract with a contractor to build new mass rapid train station in Singapore using the Public Sector Standard Conditions of Contract (PSSCOC) for construction works, (8th Edition, 2020). The contractor is responsible for the construction of the Works. Nominated subcontractors were nominated to do part of the Works. A Superintending Officer was appointed to manage the project. Answer the following questions in the context of the PSSCOC.

Explain the process of selecting and appointing nominated sub-contractors (NSCs) including the contractor's liabilities to the NSC.