1. A computer-implemented method for evaluating a machine-executable software code specification, comprising: using the computer to generate a system dependence graph corresponding to the software code specification, the system dependence graph including elements comprising nodes and edges wherein the computer evaluates the system dependence graph, the evaluation of the system dependence graph comprising: selecting a variable modified in the software code specification; providing a control operation node of the system dependence graph corresponding to a control statement in the software code specification with a preferred calibration state; traversing to selected elements of the system dependence graph, the selected elements associated with the selected variable and the preferred calibration state of the control operation node; evaluating only the selected elements of the system dependence graph; and identifying ones of the selected elements whereat a state of the selected variable is modified.