Automatic addition of contrasts

if I define contrasts for a factor variable with n levels, e.g.

contrasts(x) <- c(-2,1,1)

and I subsequently display these contrasts via


I obtain - beside the self-defined contrasts- (n-1) additional contrasts (second row):

[,1] [,2]
-2 -5.551115e-17
1 -7.071068e-01
1 7.071068e-01

Where do they come from? What do they represent? Do they hav something to do with the uniqueliy existing set of orthogonal contrasts? Thanks.