Competition law – Competition Appeal Tribunal. The defendant company, NSAR Ltd, carried out the function of accreditation and auditing under the rail training accreditation scheme on behalf of Network Rail Infrastructure Ltd (Network Rail). Accordingly, for the purpose of determining, as a preliminary issue, whether NSAR was an undertaking for the purpose of s 18 of the Competition Act 1998, the Competition Appeal Tribunal took the view that the status of Network Rail had to be considered. Having considered that status in the light of the relevant legal principles and authorities, the tribunal held that Network Rail was an undertaking for the purposes of that provision.