# In the intermediate results of RF‑SOILIN, there are red values displayed. What is it all about?

If the result values are displayed in red, it is a kind of an error message.
The defined depth z is not sufficient. The standard specifies that the depth must be calculated up to the value where sigma_Z ≦ 0.2*sigma_r. In the graphic, 0.2*sigma_r is displayed as a gray line, sigma_Z as red.

The layer structure should have such a depth that both lines intersect each other.
In Figure 01, the two lines do not intersect, so the values are displayed in red, and it is necessary to define the sufficient depth.