You can add an Item code to Catalogue items, making it easier to choose the right item, as well as making Catalogue updates easier when descriptions change.
Navigate to "Catalogues" and select the catalogue you wish to update
Note the "Code" column. This is where your item codes should be entered
Click the Edit button to switch into edit mode and enter Item codes
Enter your item code in the field called "Code"
You can also add Item codes through the import.