One of the major problems of keeping track of supply movements in a combat zone is knowing where thousands of trucks are at any one time. It's an ancient problem. Before trucks became common 80 years ago, you had lots of horse drawn wagons. The major hassle in the last century has been armies getting so huge, as has the area they are operating in. The solutions have, to date, been lots of radio and telephone messages, as well as teams of traffic controllers who stood by roads and counted trucks, and noted, from the text stenciled on their bumpers, who they belonged to. This was radioed back to headquarters where staff officers tried to make sense of who was where, and fix problems with those who weren't where they were supposed to be. Now the U.S. Army is testing a better idea. ITV (In-Transit Visibility) uses plastic tags tied to the grill of supply trucks. When this is done, data on what is in the tagged truck is sent to a web site, along with the unique code in the tag. The tags unique code is broadcasts (up to 500 meters) to a dish shaped electronic interrogator when ever the interrogator is pointed at the tag. The interrogator is attached to a satellite phone that transmits the data to a web site. Internet users with the right passwords can access this data. Traffic control teams just set up an interrogator alongside a road, tell the web site where they are, and start sending information of what trucks are passing by. The amount of communications is cut down, as are the recording errors. In military operations, there are usually a small number of MSRs (Main Supply Routes) that have to be monitored.