Overview
When you ship multiple packages together in a single FedEx shipment (called a Multi-Piece Shipment, or MPS), FedEx issues two types of tracking numbers:
- One master tracking number — represents the entire shipment as a whole.
- One per-package tracking number — unique to each individual box or parcel in the shipment.
Luminous stores and displays both, and the distinction matters particularly when you need to void or cancel labels.
How Luminous handles master vs. per-package tracking
When a multi-piece FedEx shipment is created through Luminous Label Printing, a single API call is made to FedEx covering all packages at once (up to 40 packages per shipment). FedEx responds with:
- A master tracking number shared across every package in the shipment.
- A sequence number and individual tracking number for each package (Package 1, Package 2, etc.).
Luminous records each package as a separate label entry, linked together as a group. The master tracking number is saved on each of those entries, alongside the package's own tracking number and its position in the sequence (e.g., 1 of 3).
On the fulfillment order detail view, the shipment header shows the master tracking number. The individual per-package tracking numbers are also surfaced, shown as a count indicator (for example, "+2 more") when there are multiple packages.
Why this matters: voiding a multi-piece FedEx shipment
This is where the master tracking number has the most practical impact for operators:
- FedEx only allows you to cancel an entire multi-piece shipment at once, using the master tracking number. You cannot void a single package while keeping the rest of the shipment active.
- If you try to void just one package from a FedEx multi-piece group in Luminous, the system will block the action and prompt you to void the entire group instead.
- When you void the group, Luminous makes one cancellation call to FedEx using the master tracking number, and all individual packages are voided simultaneously.
Comparison: FedEx/UPS vs. other carriers
| Carrier | Master tracking number? | Can void individual packages? |
|---|---|---|
| FedEx (direct) | Yes — one per shipment | No — must void the whole group |
| UPS (direct) | Yes — one per shipment | No — must void the whole group |
| USPS, DHL, EasyPost | No — each parcel is independent | Yes — void individually |
For USPS, DHL, and EasyPost-routed shipments, there is no master tracking number. Each parcel is treated as its own independent shipment by the carrier, so Luminous can void any single package without affecting the others.
Summary
- The master tracking number identifies the FedEx multi-piece shipment as a whole and is what FedEx uses if you need to cancel.
- Each per-package tracking number can be used to track where an individual box is in transit.
- In Luminous, voiding a FedEx or UPS multi-piece shipment always cancels all packages at once — partial voids are not supported by those carriers.