Incidence matrix according to symbol extension

x3o:s3s5s   (N → ∞)

 N |  60 |  90  60 |  80 12  verf: snid
---+-----+---------+-------
 2 | 30N |   3   2 |   4  1
---+-----+---------+-------
 3 |   3 | 30N   * |   2  0
 3 |   3 |   * 20N |   1  1
---+-----+---------+-------
 4 |   6 |   3   1 | 20N  *  tet
12 |  30 |   0  20 |   *  N  ike