If you have a list of value for any User defined Field in your customization and the better solution is to add it to the user defined codes and you can add to it at any time without a need to edit your customization as below: An example: I have a list of purchase group (410,411,412,413,…..etc) so I will add the user code type which is “Purchase group” and then I will add the codes which is (410,411,412,413,…..etc) as you can see below: