The Transportation Control Number (TCN) has many uses in the defense supply chain and is ultimately how the Defense Transportation System tracks items that process through it.  It differs from Radio Frequency Identification (RFID) which is a more recent initiative with different characteristics.   Each has their own advantages, and they can work in concert with but independently of each other.   Identifying the contents of a container by RFID requires access to the DSS database, while the TCN only requires access to the requisitions that a defense activity has placed.

For shipments of items that are made against requisitions of a single contract line item the TCN is generally comprised of the Requisition Number (REQN), with three additional characters to allow for differentiation of containers.  This is important because otherwise automated identification systems that scan containers would not know if they had read multiple containers with a particular TCN or the same TCN multiple times.

Piece Number

The Military Shipment Label (MSL) solves this problem by adding a barcoded Piece Number, which is defined by Mil-Std-129 to be the numeric value assigned to a piece (container) documented by a TCN.  When read together, the TCN and Piece Number uniquely identify each container.   The Piece Number barcode actually includes the number of pieces, information that incremented TCNs lack.  This allows one to know when all the containers of a shipment have been received.

Incremented TCN

The other approach for differentiating between multiple containers with the same MILSTRIP/Requisition Number is the addition of the three characters which follow it, that are “XXX” by default.   These three characters, in order, are:

  • MILSTRIP suffix code, which if none is “X”, actually identifies a different order not a container within the same shipment.
  • Partial Shipment Code – which is “X” when the “entire shipment unit (is) moved together”, and “A” for the first increment of a partial or split shipment, “B” for the next, and so on.
  • Split Shipment Code – which is always “X” for parties originating the shipment.  Transshipment companies use this TCN position to indicate when they split a shipment.

Incrementing TCN versus Piece Number

One must dig pretty deep into the Defense Transportation Regulations (DTR-Part II, Chapter 208 and Appendix L) to get a sense of when to increment the TCN versus the Piece Number within a TCN.  But it boils down to whether a shipment is split between multiple conveyances.  When it is, the TCN should be incremented, otherwise the Piece Number is.

Shipping multiple containers via a small parcel service (UPS, Fed Ex, etc) is open to interpretation.  Technically speaking, it depends on how one defines “conveyance”.   The most important factor is preventing containers from being confused or over counted.  Both systems protect against that, while using piece numbers has an added advantage of informing the recipient of the number of containers to expect in the shipment.  That is because the Piece barcode actual says Piece-of-Total, e.g. “7of12” while the incremented TCN is just a counter. 

Creating a TCN

In situations where a TCN is not provided by the Government, the contractor will need to create one consistent with the Defense Transportation Regulations (DTR Part II, Appendix L) for use on a Military Shipment Label.   Create a TCN by following these rules:

  1. Start with ‘X’ followed by the shipping activities CAGE code.  The ‘X’ differentiates that the address code is not a DODAAC.
  2. Enter the last digit of the calendar year and the day or the Julian date of the year the TCN is assigned.
  3. Enter the TCN serial number, by starting with an ‘A’ and then a zero-filled counter of the number of shipments made by the shipper that day, such as ‘001’.   The ‘A’ may be replaced by other alphabetic characters, allowing for 26,000 shipments per day.
  4. Follow up with ‘XXX’

The result will be a 17-characters, such as, X1HLD98015A023XXX, which would identify a container as part of the 23rd shipment made by CAGE 1HLD9 on January 15 of the most recent year ending in ‘8’.  

Combining Incremented TCNs and Piece Numbers

For shipments that must be shipped on more than one truckload, or over multiple days, the shipper must use incremented TCNs as described above.   However, for each piece within that shipment, the Piece Number would be incremented, starting from one for each increment of the TCN.   Fortunately, for shipments this complicated DLA’s Vendor Shipment Module is likely to be assigning the TCNs.