List of Customer Codes

Hey SAP gods I have a question.

So I'm trying to get a list of customer codes that would be relevant to our particular plant and am having trouble finding out how to narrow down the list. I am using XD03 and can generate a list of all customers with their customer code, but I'm not sure what I would need to narrow down the list to be plant specific. Forgive my noobness with this but can you guys help me figure out what I would need to narrow the list, if it is even possible, to customer codes that are only specific to the plant that I'm in?

Thanks!