Demonstration of track line, and overriding track line through track configuration.

    track name=clones description="Clones" visibility=2 color=0,128,0 useScore=1 url="http://genome.ucsc.edu/goldenPath/help/clones.html#$$"
    #chrom chromStart chromEnd name score
    chr22 10000000 10004000 cloneA 960
    ....