Roles are currently assigned to content that are not included in this role list. Do you want to add these roles now?
You have opened your Roles.en file, to maintain your master Role List. However, there are Additional Roles present somewhere in your Library content. These are roles that are assigned to content but are not present in your master Role List. Clicking on Yes in response to this message will add all Additional Roles to your master Role List (so you will then no longer have these Additional Roles in your Library).