Grid
The term grid describes the distance between two test points on a printed circuit board (PCB) or device under test (DUT), or the distance between two component pins or connectors. Based on the test probe, the distance is defined as the centre of one mounting hole to the centre of next mounting hole on the probe plate. There are internationally recognised grid distances which manufacturers of PCBs and connectors observe. As the definition is based on imperial units rather than metric units, the grid size is given in inches. The grid sizes are sometimes very small so the grid dimension 1/1000 inch is used. 1/1000 inch is also denoted as Mil.