1. Click on Add button
2. MeRLIN adds a new line at the end of the existing list of Codes. Provide a unique Code and  Description.
3. Now click on the Save button.
4. Now move to the User Defined Code Value tab and select the User Defined Code Type from the  available list of codes.
5. Click on the Add button to add code values.
6. Enter codes and click on save.