disclosed is a system and method for providing an effective means for making it easy to identify which holes in an interface plate are to be populated with probes and which are to be left empty . this identification of holes or apertures in a plate is used most commonly an electrical probe testing plates where a probe array is set up and inserted though the plate . the problem is that it is very difficult to double check to see if all probes are installed . with a two - tone color identifier it is easy to visually or machine read the probe plate for probe installation errors . the method employs coating the plate with a colorant and ablating colorant adjacent holes , which are either populated or empty , the difference being easy to spot .