4. 3 The Gypsy language 72 4. 4 The Gypsy Verification Environment 73 4. 5 A simple example 81 4. 6 Specification data types 91 4. 7 Future directions 95 100 4. 8 Conclusions 5 Reliable programming in standard languages 102 Bernard Carre, Program Validation Ltd. 5. 1 Introduction 102 5. 2 Language requirements for high-integrity programming 103 5. 3 The use of standard languages 108 5. 4 Programming in Pascal and Ada 110 1'19 5. 5 Practical experiences NewSpeak: a reliable programming language 6 122 I. F. Currie, Royal Signals and Radar Establishment 6. 1 Introduction 122 6. 2 Types and values 127 6. 3 Declarations and variables 132 6. 4 Guarded declarations 134 6. 5 Cases and conditionals 136 6. 6 Loops 138 6. 7 Procedures 140 6. 8 Assertions 145 6. 9 Timing 147 6. 10 Conclusion 149 6. 11 Appendix 1: summary of syntax 150 6. 12 Appendix 2: type lattice and widening 156 7 Program analysis and systematic testing 159 M. A. Hennell, University of Liverpool, and D. Hedley and I. J. Riddell, Liverpool Data Research Associates Ltd. 7. 1 Introduction 159 7. 2 The basic requirement 160 7. 3 The Liverpool experience 161 7. 4 The Liverpool experiments 162 7. 5 The LDRA Testbeds 163 Interpretation 169 7. 6 7. 7 Applicability and benefits 171 7. 8 Safety-critical systems 173 VI 8 Program analysis and verification 176 Bernard Carre, Program Validation Ltd. 8. 1 Introduction 176 8.