"ts","dur","part","a","b"
100,150,1,111,111
250,50,1,111,"[NULL]"
300,100,1,111,222
400,100,1,111,333
500,150,1,111,333
500,50,3,222,333
500,100,4,333,333
0,50,5,444,"[NULL]"
50,200,5,444,111
250,50,5,444,"[NULL]"
300,100,5,444,222
400,250,5,444,333
650,350,5,444,"[NULL]"