The present document provides the User Requirement Specifications (URSs) for the TETRA Direct Mode Operation. The present document is applicable to the specification of TETRA Release 2.1 equipment. The user requirements contained in the present document are described in non-technical terms and are based on discussions in TC TETRA WG1 and on an analysis of the results for DMO from the 2001 TETRA Release 2 Market Questionnaire and the 2007 Future of TETRA workshop [i.1].