OK thanks. I have used the G-Value filter and that is fine to remove the "null" values of for example -999. In this case I need to keep all values so LogPlot seems to be the way to go. Alternatively I could use the G-Value filter and create 2 strip logs which are then overlayed. One with values from 0-200 and a second from 200-400. Mike
My P-Data scale (gamma, in this case) is from 0 to 200, left to right. Many of my data points are greater than 200. Is it possible to clip the trace at 200 and wrap the trace with values >200 back to the 0 line of the scale?