I would like to plot X against Y in a trellis graph, wherein Y is the conditioning variable. Y represents time, but instead of distinct categories (eg, 0-10,11-20,21-30,...) I would like to use overlapping categories (0-10,0-20,0-30,...). Does anyone know how to do this, either via options in R graphics or by manipulating the data ? Thank you. Kieran Burnett