High Quality Content by WIKIPEDIA articles! 1st & Ten is the name for a computer system that generates and displays one version of the yellow first down line that a TV viewer sees during a live broadcast of a college or professional American football or Canadian football game A competing system that performs the same task using different technology is called L-VIS for Live Video Insertion System. The line, which is not physically present on the field and is seen only by the television audience, spans the width of the football field and indicates the location of the first down marker. The purpose of the line is to make it easier for television viewers to follow play on the field. Some television football broadcasts change the color of the line from yellow to red on 4th down, or show a second computer-generated line (usually blue in color) that marks the line of scrimmage.