line        the key value - should be "oneway" or "line"
100    a
1      b
10     si
1 2 3 4 5 6 7 8 9                          x's in series_1
11 13 15 18 19                             x's in series_2
21 22 23 24 25 26 27 28 29 30 31 32 33     and so it goes
41 44 46 48 49 51 52 55 57 59
63 65 66 69 75 79 83 85 88 89 90
91 92 93 94 95 96 97 98 99