The generator matrix

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

generates a code of length 21 over Z2[X]/(X^2) who´s minimum homogenous weight is 12.

Homogenous weight enumerator: w(x)=1x^0+60x^12+276x^14+354x^16+336x^18+840x^20+1176x^22+616x^24+144x^26+156x^28+116x^30+21x^32

The gray image is a linear code over GF(2) with n=42, k=12 and d=12.
This code was found by Heurico 1.16 in 0.33 seconds.