The generator matrix

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

generates a code of length 9 over Z2[X]/(X^2) who´s minimum homogenous weight is 4.

Homogenous weight enumerator: w(x)=1x^0+59x^4+258x^6+715x^8+684x^10+277x^12+50x^14+4x^16

The gray image is a linear code over GF(2) with n=18, k=11 and d=4.
As d=4 is an upper bound for linear (18,11,2)-codes, this code is optimal over Z2[X]/(X^2) for dimension 11.
This code was found by Heurico 1.10 in 0 seconds.