Assume your input is 'ABCDE' and you only want the first 3 characters of the string to be outputted (i.e. 'ABC'). What is the best way to accomplish this?
You can use a Right Character Trim function in the map to accomplish this task. It's important to understand that the Fix To Length value in this case is fixing the length of the output string, not the length of the characters being trimmed.
If mapping the data from a source profile in a map, leave the 'Original String' field blank, since you'll map the source field to the Original String field of the function. For our example here, we'll set the 'Fix To Length' value to 3.
Within the map, connect the source profile element (in this case 'Rating') to the 'Original String' field in the function and the 'Result' field of the function to your destination field (in this case 'CUST_REF'.
This should produce the following:
Original innput (Rating): ABCDE
Output (CUST_REF): ABC