residual sat(Site).ar1(Row).ar1(Column)ASReml now allows this specification when there is only one row/column, suppressing estimation of the non-estimable parameter. This qualifierer resets the limit to 0.75 or the value specified. !S2LIMIT limits the size of the residual variance in a multi-environment spatial analysis to a tenth of the average spatial residual variance across all environments, fixing it at that small but not unreasonable value if the updated value is smaller. The motivation is that occasionally in unreplicated trials with a nugget variance also fitted, the spatial variance is poorly estimated and will otherwise go to almost zero which may mess up estimation of other terms in the model.