We sketch a logic model for representing systems analysis diagrams. The discussion is limited to diagrams from the OMT methodology of Rumbaugh et al., although no genuine loss of generality results. In developing our logic model, we have followed where appropriate (for state transition diagrams) the logical representation theory developed by Parsons for the semantics of VP modifiers. That semantics, as does systems analysis, views the world in terms of states and events. That the logical representation techniques used by Parsons are so useful for systems analysis strongly suggests that the confluence of terminology is more than coincidence, more than superficial. Tthroughout we stress the useful deductions that can be made automatically with our logic model, deductions that are not possible automatically with mere diagrams. We conclude that the program of representing systems analysis diagrams in logic holds much promise.