The generator matrix

 1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  X  1  1  1  1  1  1  1  1  1  X  X  X  X  1  X  X  X  1
 0  X  0  0  0  0  0  0  0  0  0  0  0  0  X  0  0  0  0  0  0  0  0  0  X  X  X  X  0  X  X  0  X  X  X  0  X  X  X  X  X  0
 0  0  X  0  0  0  0  0  0  0  0  0  0  0  X  0  0  0  0  X  X  X  X  X  X  X  0  0  0  0  X  X  X  X  X  0  0  X  X  0  0  X
 0  0  0  X  0  0  0  0  0  0  0  0  0  X  0  0  0  X  X  X  X  X  X  X  0  X  X  0  X  X  X  X  0  X  X  X  X  X  X  X  X  X
 0  0  0  0  X  0  0  0  0  0  0  0  0  X  0  X  X  X  X  X  X  0  X  X  X  0  0  X  0  X  X  X  0  0  X  0  0  X  0  X  X  0
 0  0  0  0  0  X  0  0  0  0  0  0  X  0  0  X  X  0  X  X  0  X  0  X  0  0  X  X  X  X  X  0  X  X  X  0  0  X  X  X  0  0
 0  0  0  0  0  0  X  0  0  0  0  0  X  0  0  0  X  X  X  X  0  X  X  0  X  X  0  X  X  0  X  X  0  0  0  X  0  X  X  0  X  0
 0  0  0  0  0  0  0  X  0  0  0  X  0  0  0  0  X  X  0  X  0  0  0  X  0  X  X  X  X  X  0  X  0  X  0  0  0  0  X  0  X  X
 0  0  0  0  0  0  0  0  X  0  0  X  0  0  0  X  0  0  X  0  X  0  0  X  X  0  X  X  X  X  0  X  X  X  0  X  X  X  0  X  0  X
 0  0  0  0  0  0  0  0  0  X  0  X  X  X  X  X  0  0  0  X  0  0  X  X  0  X  0  0  0  X  0  X  0  0  0  0  X  X  X  0  X  0
 0  0  0  0  0  0  0  0  0  0  X  X  X  X  X  0  0  X  X  X  X  X  0  X  X  X  X  X  0  X  0  0  0  0  X  X  0  X  0  X  0  0

generates a code of length 42 over Z2[X]/(X^2) who´s minimum homogenous weight is 30.

Homogenous weight enumerator: w(x)=1x^0+62x^30+114x^32+162x^34+255x^36+401x^38+664x^40+775x^42+659x^44+456x^46+239x^48+128x^50+90x^52+57x^54+22x^56+7x^58+3x^60+1x^68

The gray image is a linear code over GF(2) with n=84, k=12 and d=30.
This code was found by Heurico 1.16 in 2.83 seconds.