R help - Jun 2008 - some r code for linear mixed model

Hello everyone:
  I have some quesions about the R code for linear mixed model,hope some one
can give me some hints,thanks a lot~
  Say:
  we have A B C three factors
  (i)A is fixed ,B and C are random,and B is nested in C,so the R code for
this case would be:
   case1<-lme(y~A+B+C+......,random=~B|C)
where "B|C" actually mean B is nested in C, is it correct?
  (ii)and if I update the case as:
  updatedcase1<-update(case1,random=~1|C), did I just remove the random
effect of B, and only random effect of C left in the model? is it correct?

 (iii)A ,B,is fixed ,but C is random,no nested case,how am I gonna write the
R code,since
      lme(y~A+B+C+.....,random=~C) lead to error,

(iv)for the case1,if I wirte this
   updatedcase2<-update(case1,random=B-1|C)
where,"B-1|C",what this syntax stand for in R?


thank you guys very much~

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