I have many grade fields that all require a calculation to get the subject grade transformed into a number so they can be averaged for the different semesters. The calculation I am using is: Position("FDCBA"; Left(fieldLet1; 1); 1; 1) - 1 + Choose(Position("+-"; Right(fieldLet1; 1); 1; 1); 0; .33; -.33). This works fine but I don't want to duplicate it for each subject. Is there a way to write it once (maybe as a custom function) and use it for all the subject grades?