The generator matrix

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

generates a code of length 42 over Z2[X]/(X^2) who´s minimum homogenous weight is 44.

Homogenous weight enumerator: w(x)=1x^0+12x^44+3x^48

The gray image is a linear code over GF(2) with n=84, k=4 and d=44.
As d=44 is an upper bound for linear (84,4,2)-codes, this code is optimal over Z2[X]/(X^2) for dimension 4.
This code was found by Heurico 1.16 in 0.0117 seconds.