The standards and guidance used in safety-critical systems development are subject to varying degrees of interpretation. This is most apparent when the guidance from one document is used as a means of compliance for another. One such example is Def Stan 00-56; it sets a number of relatively abstract goals and encourages the use of other standards to meet those goals. In this paper, we present a modelling technique that helps the system developer to explain how the use of one standard meets the needs of another by way of explicit items of evidence. We illustrate the model with some examples from recent work on Def Stan 00-56 and IEC 61508, and discuss some of the critical issues in enabling more general use of such explicit representations.