Abstract: A tool and method that automatically formats an Engineering Change Order (ECO), in a programming language suitable for processing by an Electronic Design Automation (EDA) tool, in order to specify metal-only design changes to complex hardware data-paths through changes in the netlist. The invention comprises an initial import component that imports a working netlist which serves as the baseline on which the tool operates. The tool further comprises four components: a bus extraction component, an index creation component, a text editor, and an ECO generation component. One or more buses are extracted from the working netlist and tabulated into an index table. The user uses a test editor to modify the index table to create a modified index table that embodies the desired design change. Finally, the ECO generation component automatically reconfigures the modified index table into an ECO format in a language usable by automated physical design tools.