The status codes for the Shipment Tracking - Unified API are the following: pre-transit, transit, delivered, failure, and unknown. You can find more information about this in the API documentation under Reference Docs, then click on the "GET" Endpoint, scroll down, and click "Show Data Schema" under the Code 200 section.
Definitions of status codes:
Pre-transit : Currently awaiting shipment, and tracking will be updated when received
Transit : Carrier has accepted or picked up from shipment from the shipper. the shipment is on the way
Delivered : The shipment was delivered successfully
Failure: A shipment encounters an unforeseen event, e.g., customs, expired (consignee doesn’t pick up from service point), returned, etc.
Unknown: A simplified status code is not available.
Additional status Codes like: "Out for Delivery", "Return to Origin", and "Ready for Pick-up", are planned to be added tot the API, but are not available yet.
Note: The Shipment Tracking - Unified API connects to many backends to receive shipment data. As a result, these status codes may differ depending on the DHL division.