Contents Foreword 1 Scope 2 Normative References 3 Terms and definitions 4 Classification and technical requirement of city gas Annex A (Normative) All kinds of pure gas for preparation of test gas Annex B (Normative) All kinds of pure gas property value for preparation of test gas Annex C (Informative) Comparison between this Standard and BS EN437: 1994 and EN 30-1-1:1999