I have a question about the Wald test F-statistics that are calculated when the anova() command is used on a singular gls or lme object. As I recall from my linear models class, the Wald test examines H0: C'B = d0 vs Ha: C'B != d0. Does anybody know how this C matrix is constructed in R? Is there a way to see the C matrix that R is using? In my situation, I'm looking at marginal ANOVA tables and would like to know how the other factors, and in particular the interaction terms, are being treated for a given row of the table. I'm assuming that some sort of averaging takes place but can't find anything about it in the documentation I have. Thanks, Alan