What is the Nickname used for?

The nickname field is used for your reference so you can easily locate your declaration in your Account Dashboard.

This field is mandatory and therefore must be completed before you can proceed. Once the nickname has been entered it cannot be amended. 

The nickname is different from the Unique Reference Number as this is only used internally and is never passed on to HMRC. 

You can use your own internal reference here, or create a memorable naming structure just for your CustomsLink entries.