A lithography reticle advantageously includes "proximity effect halos" around tight tolerance features. During reticle formation, the tight tolerance features and associated halos can be carefully written and inspected to ensure accuracy while the other portions of the reticle can be written/inspected less stringently for efficiency. A system for creating a reticle data file from an IC layout data file can include a processing module and a graphical display. The processing module can read the IC layout data file, identify critical features and define a halo region around each of the critical features. The graphical user interface can facilitate user input and control. The system can be coupled to a remote IC layout database through a LAN or a WAN.