By default, when you import csv files into Sugar modules in Update mode, The import update all the informations of the lines.
That is to say, if a field is blank into the CSV file then the import will erase the content of the field into SugarCRM.
My wish will be to have the possibility to add a value (for example 'NULL') to inform the import to not update the value into SUGAR. Instead of replace the value.
PS : Hope it is clear as english is not my native language.