The generator matrix

 1  0  1  1  1  1  1  1  1  1  1  1
 0  1  1  3 5X+2  6 5X+4  5  0 5X+1  3 5X+2
 0  0 5X  0 5X  X 5X  X 6X 2X  X 6X
 0  0  0  X 4X 4X 3X 6X  0 6X  X 6X

generates a code of length 12 over Z7[X]/(X^2) who´s minimum homogenous weight is 56.

Homogenous weight enumerator: w(x)=1x^0+210x^56+1176x^60+480x^63+8232x^66+14112x^67+468x^70+49392x^73+42336x^74+888x^77+354x^84

The gray image is a linear code over GF(7) with n=84, k=6 and d=56.
This code was found by Heurico 1.16 in 0.584 seconds.