AE                      Calculate Agronomic Efficiency
IE                      Calculate Internal Efficiency (IE)
NBI                     Calculate N Balance Intensity (NBI)
NHI                     Calculate N Harvest Index (NHI)
NP                      Calculate Nitrogen Productivity (NP)
NRE                     Calculate Fertilizer-N Recovery Efficiency
NRE15                   Calculate Isotope-Based Recovery Efficiency of
                        N-Fertlizer (NRE15)
NUEFC                   Calculate NUE of a Food Chain (NUEFC)
NUEbal                  Calculate NUEbalance
NUEcrop                 Calculate NUEcrop
NUEsoil                 Calculate NUEsoil
NUEyield                Calculate NUEyield
NUpE                    Calculate N Uptake Efficiency (NUpE)
NUtE                    Calculate N Utilization Efficiency (NUtE)
NdfF                    Calculate N derived from Fertilizer (NdfF)
PE                      Calculate Physiological Efficiency
PFP                     Calculate Partial-factor Productivity (PFP)
PNB                     Calculate Partial N Balance
TNdfF                   Calculate Total N derived from Fertilizer
                        (TNdfF)
VNF                     Calculate Virtual N Factor (VNF)
ecoNUE                  Calculate NUEecology
sNBI                    Calculate N Balance Index of a System (sNBI)
sNUE                    Calculate NUE of a System (sNUE)
