I would like to create an "x,y" type plot ("scatter graph" in Excel terms) in which the "x" array is continuous, but some of the "y" values are invalid because the formula has a limited valid range. I can use an IF to substitute "" or "nil" "invalid" or something for the invalid "y" values. However, what I want and haven't found is something to plug in that will not be plotted as a value. "", text and "ERR" are all plotted as zero values. Is there something I can put in the cell that the graphing routine will just skip rather than treating it as a zero?