System checked as an APSTS(v) with v=19 on {A,B,0,1,...(v-3)} with 
A=v-2, B=v-1, a block AB0, a generic labelling w.r.t. {A,B}, 
and no blocks 0w(w+4) (mod v-2). 57 blocks follow.

   0   1   6
   0   2  11
   0   3  10
   0   4   7
   0   5  14
   0   8  15
   0   9  16
   0  12  13
   0  17  18
   1   2  17
   1   3   9
   1   4  18
   1   5  12
   1   7  16
   1   8  10
   1  11  14
   1  13  15
   2   3  15
   2   4  13
   2   5  16
   2   6  10
   2   7  18
   2   8  14
   2   9  12
   3   4  17
   3   5   7
   3   6  18
   3   8  12
   3  11  13
   3  14  16
   4   5  11
   4   6  14
   4   8   9
   4  10  15
   4  12  16
   5   6  17
   5   8  13
   5   9  15
   5  10  18
   6   7  12
   6   8  16
   6   9  13
   6  11  15
   7   8  17
   7   9  11
   7  10  13
   7  14  15
   8  11  18
   9  10  17
   9  14  18
  10  11  16
  10  12  14
  11  12  17
  12  15  18
  13  14  17
  13  16  18
  15  16  17

cycle on {A,B} of length  16
   1   2   7   8  11  12  15  16  13  14
   9  10   5   6   3   4

 pairs with 0 and differences mod v-2
   1   6      5
   2  11      8
   3  10      7
   4   7      3
   5  14      8
   8  15      7
   9  16      7
  12  13      1