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This paper explores what it means to be a refinement relation. After picking on one of the uses of the term, we consider the variety of relations which are captured by this definition. Each refinement relation defines a property. Each property represents the viewpoint of a different specifier role, allowing us to structure specifications in a proof oriented way. Note This paper has been revised to bring it closer to standard Z (as policed by CADiZ R3.10 [21]) than the original version was. I made the minimal number of changes to do this. If I was writing it from scratch today I would make several changes to the style (but not the meaning) of the presentation of formal text, and include formal proof scripts of the (now formally stated) conjectures. I would also make certain changes to the style of the informal text. If you believe that one should apologise for the lapses of youth, I hereby do so.