The present document outlines the process employed by TC TETRA Working Group 1 in generating user requirements in general@ and the methodology used for creating User Requirements Specifications (URSs) for Release 2.1 in particular. It also covers the process of identifying interdependencies@ which is considered important for ensuring that various stand-alone URSs fit together into an integrated and coherent URS for TETRA Release 2.1 as a whole. The present document is applicable to the specification of TETRA Release 2.1 equipment. NOTE: Some of the parts may stay as TETRA Release 2@ but are part of the present set of URSs. Each of the work areas of the TETRA Release 2.1 programme is covered by its own stand-alone URS. The URSs were produced by the membership of WG1@ who are responsible for capturing and defining user requirements for TETRA.