I am trying to use nested variables in glm because I have a non-normal dependent variable potentially explained by nested categorical and continuous variables. I see how to do this in anova (e.g., anova allwasps PlotCode / TmtCode|PlotCode / YR / Month/YR), but if I try the same with glm (e.g., glm allwasps PlotCode / TmtCode|PlotCode / YR / Month/YR, family(poisson)), I get the error message "'/' not allowed in varlist". Is there a way of nesting variables in glm syntax? Thank you.