1. In a software system, an Electronic Design Automation (EDA) software application program for facilitating an Engineering Change Order (ECO), said software program comprising: a circuit description described in a hardware description language (HDL) comprising a pre-ECO circuit description comprising a pre-ECO Register Transfer Level (RTL) netlist, and a ECO circuit description comprising an ECO circuit RTL netlist, said ECO circuit RTL netlist representing said pre-ECO RTL netlist modified by an ECO; an ECO RTL netlist software module for generating said ECO RTL netlist; a final ECO gate-level netlist synthesis software module for generating and outputting a final ECO gate-level netlist, said ECO gate-level netlist corresponding to said ECO RTL netlist and describing said ECO circuit.