I’ve been reviewing the conceptual data area, what I have called the ‘Information Model’ and I’ve come to the conclusion that the Data Structure Diagram is what I’m after, albeit with arrows, not crows feet. One of the advantages of the DSD is that you can describe an interface fairly readily with it and put objects inside each other. I think the crow’s feet belong at the Logical E-R diagram level. Thinking about these areas does make you realise how limiting the conventional UML class diagram can be in conceptual and design thinking.