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; traversing to selected elements of the system dependence graph, the selected elements associated with the selected variable, wherein traversing to the selected elements of the system dependence graph includes tracing the selected variable from its starting point whereat the selected variable is modified and working in a reverse analysis fashion following selected nodes and selected edges until arriving at an initial point for the selected variable; 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.