When NHRA or IHRA runs a national or sanctioned divisional points meet they bring and use there own timing equipment. otherwise tracks have their own equipment they use and can be set up to show .000 or .500 based on the manufacture's (compulink, chrondek, TSI,) software installed into that perticular system. As an example, Byron Dragway near Rockford IL. and Indianapolis raceway park used a compulink III system that showed .500 as reaction time, Great Lakes Dragaway in Union Grove Wi. used chrondek that showed .000, Cordova Dragway used a TSI "SD" super system that showed .000 and US 131 dragway in Martin Mi. used the same TSI system and showed .500 as a perfect reacton time. My ET slips from the 2 times I raced at BMP in 98 and 02, show a compulink startrak syst, that show a .500. Hope this Info helps..