Clamp
This modifier layer can be used to restrict value ranges at their limits. Assuming you have values from 0 to 1, but want values between 0 and 0.8, set Maximum to 80%. Values between 0.8 and 1 are truncated and are all 0.8.
Please note that all field lists automatically crop values less than 0 and greater than 1 by default (but this can be deactivated).
Example
A spherical field with a linear falloff in value is clipped by the "Clamp" modifier layer. Minimum and Maximum are varied.