Here is the process: 
  1. Go to File Maintenance > Profiles > Profile Code Maintenance > Affiliation
  2. Click on the New button in the upper left.
  3. Enter the Affiliation Code and its description.
  4. If the new Affiliation will be part of an existing group, then you can add it to that group on the right. 
  5. If the new Affiliation Code will be a group code for other existing codes, then you can add those sub codes on the bottom. 
  6. Click the Save button in the upper left.
You should be all set to add the new code to profiles as needed.