R help - Mar 2009 - question of correlation structure in gls

Dear R users,

I want to fit a model with within-subject correlations but with no random
effects.  So I could use gls to set correlation=corSymm(~1 | group).  Here
the problem I encountered is that I have 90 groups, and for the first,
second and third 30 groups I want them to have three different
unstructured correlation structures.  Can I achieve that in gls() of the
nlme package?

Thank you!

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