crback.setup <- function(y)
{
	yname <- as.character(substitute(y))
	if(!is.category(y))
		y <- factor(y, exclude = NA)
	y <- unclass(y)	# in case is.factor
	ylevels <- levels(y)
	kint <- length(ylevels) - 1
	y <- as.integer(y - 1)
	reps <- ifelse(is.na(y), 1, ifelse(y > 1, kint - y + 1, kint))
	subs <- rep(1:length(y), reps)
	cuts <- vector("list", kint + 2)
	cuts[[1]] <- NA
	for(j in 0:kint)
		cuts[[j + 2]] <- if(j < 1) 1:kint else j:kint
	cuts <- unlist(cuts[ifelse(is.na(y), 1, y + 2)])
	y <- rep(y, reps)
	Y <- 1 * (y == cuts)
	labels <- c(paste(yname, "<=", ylevels[2:kint], sep = ""), "all")
	cohort <- factor(cuts, levels = 1:kint, labels = labels)
	list(y = Y, cohort = cohort, subs = subs, reps = reps)
}