If you’ve chosen to include Label Messages in your Printing Setup, it helps to know where the message will appear on the FedEx shipping label.
For information on how to include these Label Messages (for example, add an Order Number, SKU, or custom message), please review the article: How can I add order information to my labels?
On most FedEx shipping labels, there are three available fields in which you can insert a label message. The fields are labeled REF, INV, and PO, and they correspond to Label Messages #1, #2, and #3, respectively.
On FedEx Commercial invoices, Message #1 appears in the Special Instructions portion on the bottom left, and Message #3 appears under Purchase Order No. at the top right of the document.
Note: FIMS services do not support Label Messaging and FedEx SmartPost only allows Message Field 1.