The generator matrix

 1  0  0  0  0  1  1  1  1  X  1  1  X  1  1  1  0  X
 0  1  0  0  0  0  0  0  0  1  1 X+1  X  1  1 X+1  X  1
 0  0  1  0  0  0  0  1  1  1 X+1  X  1 X+1  0 X+1  1 X+1
 0  0  0  1  0  0  1  1  X X+1 X+1  0 X+1  0  1  1  X  X
 0  0  0  0  1  1  1  X X+1 X+1  X  1  0  0  0 X+1  0 X+1
 0  0  0  0  0  X  0  0  0  0  0  0  X  X  X  X  0  X
 0  0  0  0  0  0  X  0  X  0  X  X  X  0  X  X  X  0

generates a code of length 18 over Z2[X]/(X^2) who´s minimum homogenous weight is 12.

Homogenous weight enumerator: w(x)=1x^0+207x^12+470x^14+818x^16+1042x^18+942x^20+442x^22+140x^24+30x^26+3x^28+1x^32

The gray image is a linear code over GF(2) with n=36, k=12 and d=12.
As d=12 is an upper bound for linear (36,12,2)-codes, this code is optimal over Z2[X]/(X^2) for dimension 12.
This code was found by Heurico 1.16 in 0.935 seconds.