A grid is displayed on a display device to provide a reference for a geographic area including an excavation site. Also disclosed herein is a method of making the composistions in which molybdenum or Fe\u2014Mo is added to the MnS compound to improve machinability and to obtain a more stable MnS compound, thereby reducing any change in weight and size in a sintering process. The bag is made using cross-web technology with the tear strings being attached to the lengths of zipper and the free ends of the strings being concertinaed in the top seal zone.