[Freesurfer] Group analysis, contrasts

I'm trying to set ut a freesurfer group analysis. In my fsgd file there are four groups/classes and 2 variables, like so:

GroupDescriptorFile 1 Title Class Class1 Class Class2 Class Class3 Class Class4 SomeTag

Variables Variable1 Variable2 Input subj1 Class1 49 1 Input subj2 Class2 50 2 Input subj3 Class3 51 3 Input subj3 Class4 52 4 Input...

I'm a bit puzzled as to how I should set up the contrasts. With DODS, there should be a matrix of 12 regressors, and I want to model how thickness varies with Variable2, ignoring the effects of Variable1 and Class. Should my contrast be

0 0 0 0 0 0 0 0 0.25 0.25 0.25 0.25 or 0 0 0 0 0 0 0 0 1 1 1 1

or something completely different?

I have tried both contrasts, and they yield identical (and plausible) results.

Kind Regards, Per Selnes