What does the "effects" vector from geepack fitted object mean?

Dear All,

I am writing to ask what the " gee1[["effects"]]" vector calculates in the geepack package. 

library(geepack)
data(dietox)
dietox$Cu     <- as.factor(dietox$Cu)
mf <- formula(Weight ~ Cu * (Time + I(Time^2) + I(Time^3)))
gee1 <- geeglm(mf, data=dietox, id=Pig, family=poisson("identity"), corstr="ar1")
gee1[["effects"]]# a vector of the regression coefficients plus ~848 estimated "effects" that are not residuals. I have no idea what they mean.
View(gee1)

Best regards,
John