Correlation variance models can be appended with v eg. idv() to add a common (homogeneous) variance or with h (eg., idh()) to add a separate (heterogeneous) variance for each level of the factor.
Correlation variance models can be appended with v eg. idv() to add a common(homogeneous) variance or with h (eg., idh()) to add a separate (heterogeneous) variance foreach level of the factor.