The hard limits trigger if the value inputted is either less than the abs_min tag or above the abs_max tag. Hard limits are established for values that will break the science model if inputted, i.e. a percentage passed into a fraction area. The default color for a cell that exceeds the hard limits is magenta.
If any values in the set of files for the current management file exceed the hard limits, you will not be able to save the file and use it for your WEPS run.