The generator matrix

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

generates a code of length 21 over Z2[X]/(X^2) who´s minimum homogenous weight is 16.

Homogenous weight enumerator: w(x)=1x^0+369x^16+885x^20+702x^24+90x^28+1x^36

The gray image is a linear code over GF(2) with n=42, k=11 and d=16.
As d=16 is an upper bound for linear (42,11,2)-codes, this code is optimal over Z2[X]/(X^2) for dimension 11.
This code was found by Heurico 1.10 in 238 seconds.