Usage: field fieldName [threshold parameter] value
This form set the threshold parameters for the field. These parameters are used during the nonlinear solve to check and adjust nodal values that may cause nonconvergence in the nonlinear solve. The parameters that can be set are -thresholdValue, -warnThreshold, and -minimumAfterUpdate.
If the model requests -checkThresholds (default), a single warning message is printed if any nodes fall below the warn threshold after a nonlinear update.
If the model requests -adjustThresholds (default), any nodes that violate the threshold value condition are set to be either the minimum after update (default) or the old concentration (if -minConcIsOldConc is specified).
If the model requests -printThresholdViolation, all nodes that violate the warning threshold value are printed.
The default values are 0 for -thresholdValue, 0 for
-warnThreshold, and 
for
-minimumAfterUpdate. These are reasonable for most
concentration fields.
If thresholds are adjusted after the last nonlinear update (i.e. convergence is detected), dose conservation may be violated, so the default is to -failIfHadThresholdViolation. Note that although node that fall below the threshold value may be adjusted, only nodes that fall below the warn threshold value will be considered to be a violation. The split of values provides for robust nonlinear solution (i.e. recombination can't become generation because of an incorrect sign) without unnecessary repeating of time steps due to numerical noise leading to insignificant negative values after an update.