1) Example of using a Python function in the expression to convert field values to upper case Expression: (!TS_ZONE!).upper() 2) Example of accessing properties of feaure geometry to convert area from meters to feet. Ths provides easy acces to the area and length properties of a shape fie. Expression: MetersToFeet(float(!SHAPE.AREA!)) Code Block: def MetersToFeet(area): return math.pow(3.2808, 2) * area 3) Example of reclassifying a range of values. Expression: Reclass(!WELL_YIELD!) Code Block: def Reclass(WellYield): if (WellYield >= 0 and WellYield <= 10): return 1 elif (WellYield >10 and WellYield <= 20): return 2 elif (WellYield >20 and WellYield <= 30): return 3 elif (WellYield > 30): return 4 4) The Python expression and code block used in Calculate Value to check the existence of a field. Expression: CheckField(r"%input_features%", "%field%") Code Block: import arcgisscripting gp = arcgisscripting.create() def CheckField(in_Table, in_Field): fields = gp.ListFields(in_Table, in_Field) if fields.Next(): return 0 return 1