NLS_NUMERIC_CHARACTERS in SQL loader control file

I am using a Control File to import data from a CSV file into a table, using sqlldr to import the data, where a large number of fields are numeric values with integer and decimal part separated by dots. The Control File works just fine because I cast the number to the input my table expects by using "TO_NUMBER(:MyVariable, '9999999999D999999', 'NLS_NUMERIC_CHARACTERS = ''.,''')" Although the control file works just fine I would like to know: Is it possible to use: ALTER SESSION SET NLS_NUMERIC_CHARACTERS = "," In this way I don't mind about differences between character used in NLS and the one used to create the file, nor i mind about the actual number of decimal significative number.