/* generate list of series and overplots */
_serlist()
{
        local i = 1, s = "", p, nitems;

        /* if a chart plot, get each trace */
        if ((itemtype == 9) || (itemtype == 2 && getplottype(0) == 6))
        {
                nitems = numitems + itemcount - 1;
        }
        else
        {
                nitems = numitems;
        }
        do
        {
                p = sprintf("%d", i);
                if (i < nitems) p = strcat(p, strescape("\n"));
                s = strcat(s, p);
        }
        while (++i <= nitems);
        return(s);
}