RFID for the Department of Defense: The DoD mandate

This standard is primarily concerned with the informational content of the labeling on shipments to the DoD. It includes requirements for labels that are intended to be read by humans or machines or both. MIL-STD-130 does not discuss RFID tag content directly, but the requirements for machine-readable labeling are written broadly enough to be useful for that purpose.

EPC tag standards version 1.1 Rev. 124

EPCglobal; April 1, 2004

The EPC standard is the authoritative source for how information on an EPC-compliant RFID tag is enclosed. All of the various encoding formats are defined in this specification.

Key terms The standard on military markings (MIL-STD 129P) contains five pages listing acronyms followed by seven more pages of definitions. Here are a few of the terms that are particularly relevant to the subject of RFID tagging:

TIMELINES

The DoD has divided its mandate into three phases, with each phase being year apart. In the first phase, only a limited number of suppliers, items and receiving depots are covered. The second phase expands the lists quite a bit, and the third phase covers everything. Details of what products and which destinations are covered by each phase are given as follows:

Phase 1—January 01, 2005

In the first phase of the RFID implementation plan (which began on January 1, 2005), only a limited number of items are required to be tagged, and then they should be tagged only when they're going to a limited set of destinations.

In particular, the following classes are covered in Phase 1:

The following destinations are covered in Phase 1:

The Phase 1 requirements apply to individual cases, cases that are part of a pallet load of products and to the pallets themselves. Individual items aren't required to have RFID labels in Phase 1. The requirement for individual item labels begins with Phase 3, on January 1, 2007.

Phase 2—January 1, 2006

Phase 2 of the RFID mandate begins on January 1, 2006. Under the requirements of Phase 2, all of the materials and destinations from Phase 1 continue and many more are added. Some of the materials covered under Phase 2 (e.g., ammunition) cannot be labeled with RFID tags until safety certifications have been completed. Also, all materials in Class I are included in Phase 2. In

Phase 1, only a subset of Class I materials is covered.

The classes covered in Phase 2 are:

The shipping destinations covered by Phase 2 include both destinations from Phase 1 plus the following:

Marine Corps maintenance depot, Albany, GA, and Barstow, CA

Army maintenance depot, Anniston, AL. Corpus Christi and Red River, TX and Tobyhanna, PA

Air mobility command terminal, Charleston Air Force Base, Charleston, SC, Dover Air Force Base, Dover, DE, Naval Air Station Norfolk, Norfolk, VA, and Travis Air Force Base, Fairfield, CA

Air logistics center, Hill Air Force Base, Ogden, UT, Tinker Air Force Base, Oklahoma City, OK, and Warner Robbins, GA

Naval aviation depot, Cherry Point, NC, Jacksonville, FL, and North Island, San Diego, CA

Defense distribution depot, Albany, GA, Anniston, AL, Barstow, CA, Columbus, OH, Cherry Point, NC, Corpus Christi, TX, Hill Air Force Base, Ogden, UT, Tinker Air Force Base, Oklahoma City, OK, Norfolk, VA, Jacksonville, FL, Puget Sound, WA, Red River, TX, Richmond, VA, Tobyhanna, PA, North Island, San Diego, CA and Warner Robbins, GA.

Phase 3—January 1, 2007

Beginning with Phase 3, everything shipped to any DoD location must be identified with an RFID tag. This includes the requirement that individual units have their own tags.

IMPORTANT CONSIDERATIONS

The DoD allows its suppliers wide latitude in deciding how to meet the mandate. There are, however, a many compatibility and suitability standards that must be met.

One area that the mandate doesn't cover is the use of active tags (tags with internal batteries that allow them to be used at longer ranges and higher speeds, but force them to be much larger than passive tags).

The DoD allows its suppliers wide latitude in deciding how to meet the mandate. There are, however, a number of compatibility and suitability standards that must be met.

The DoD currently requires active tags on a wide variety of materials and in a number of specialized applications. The mandate, however, does not apply to those items. The mandate for RFID labeling is only concerned with passive tags.

TAG SELECTION

In order to comply with the mandate, new materials being shipped to the DoD must be tagged so that each item can be uniquely identified using only the information in the tag. Tags that satisfy this requirement are known as "license plate" tags.

The DoD's stated long-term goal is to move to the use of EPC Class 1, UHF Generation 2 tags. These tags are not currently available for general use, so existing Class 0 and Class 1 tags will be accepted for near-term use. When the Class 1, Gen 2 tags become available, the DoD will announce dates for the current tags to "sunset," meaning that on a certain date, tags that are currently compliant will become noncompliant. After the announced dates, only the new tags will be accepted. In the interim, existing 64-bit tags will be accepted, although they are not preferred. After the sunset dates, however, only 96-bit tags will be allowed.

TAG-OPERATING FREQUENCY

Passive tags are required to operate in the 860- to 960-mHz frequency band. For reference, existing container-tracking systems use active tags and operate in the 433- to 434-mHz band.

TAG READABILITY

Tags must pass certain readability requirements, such as when they're passing through a portal. The tag must be readable from a distance of up to 3 m (3.3 yd) while traveling at a speed of up to 10 miles/hr. One example of this is when a pallet of material is being carried by a forklift through a doorway equipped with RFID readers.

When the tag is on a conveyor, it must be readable from a distance of 1 m (1.1 yd) while moving at a speed of up to 600 ft/min. Materials on pallets aren't expected to be placed on conveyors. This requirement applies to cased goods and individual items (after January 1, 2007).

ENCODING STANDARDS

Suppliers can choose from two encoding standards, both of which must include a unique identifier. If the supplier is a member of EPCglobal? and has its own unique EPC Manager number, then products can be tagged with one of the following codes (as defined by EPCglobal):

If the supplier isn't a member of EPCglobal, the DoD has defined an RFID encoding scheme that's based on either the Commercial And Government Entity (CAGE) code or the North Atlantic Treaty Organisation (NATO) Commercial And Government Entity (NCAGE) code. In the DoD scheme, the CAGE/NCAGE code becomes the unique supplier identifier for the supplier. The CAGE/NCAGE code is a five-byte, alphanumeric string, assigned by the government to a particular institution. When it's used in a 64-bit tag, only 30 bits are allocated to the CAGE code. What is normally a 40-bit string is compressed into 30 bits by removing the two most significant bits of each character in the string (since only upper-case letters and numbers are used in CAGE and NCAGE codes, the remaining 30 bits do not lose any uniqueness). When the CAGE code is used in a 96-bit tag, it's padded on the left with an ASCII character (hex code 0x20) to be 48 bits in length.

COSTS

Unlike Wal-Mart's suppliers, DoD suppliers have the option of setting their prices to cover the costs of compliance. There are also materials that must be tagged. There is an explicit schedule for when certain materials must have RFID tags applied to them for the DoD. But there are exceptions. Eventually, everything shipped to the DoD must be identified by an RFID tag. However, there are two notable exceptions to this rule:

Bulk commodities

Commodities that are normally shipped in tanks, pipelines or by bulk transportation do not need to be tagged. For example: sand, water, coal and animal feed are exempt.

Explosives, ammunition

Requirements for tagging any materials that could explode will be established after testing, in order to determine what effects the presence of radio-frequency energy will have in their environment.

SMART LABEL PLACEMENT

When applying an RFID smart label to a case or an item, the DoD specifications give very detailed rules for where the label must be placed. In practice, the rules follow common sense:

WHAT TO PRINT

The printed part of the smart label will include both human-readable and machine-readable information. This printed information provides a backup method of describing the material being identified. If the material is in a place where RFID reading capability is not available or where there's no connection to the database, the printed bar-code information will be used.

The precise information that must be printed in the human-readable information (HRI) portion of the smart label will be specified by the contract between the supplier and the DoD. In most cases, though, the DoD says there is a standard set of fields that will be expected.

The common items on the label include the following (note that some of these may not apply in all situations): Enterprise ID, part number, lot number, serial number, part name, "U.S.," which indicates that the item is the property of the U.S. Government, contract and/or purchase-order number, national stock number and any special characteristics. In addition to the common information, some materials will be required to include detailed information, such as manufacture date, lot number, acceptance date, weight, specifications, volume, documentation reference number and matched-set identification.

Human-readable information must be printed in all capital letters using a sans-serif font such as Arial.

MACHINE-READABLE PRINTING

The machine-readable portion of the printing is usually in the form of a bar code. Industry-standard formats and encoding schemes are used to generate the actual bar code. The content of the bar code must be a unique identifier for the material.

THE DATA COMPONENT

The ability of the smart label to hold electronic data is what allows it to be used to meet the DoD mandate. Since the mandate specifies the use of passive 96-bit tags, the data content is limited to a simple license plate (note that while 64-bit tags are allowed for near-term shipments, these 64-bit tags will be phased out as soon as possible).

UNIQUE SERIAL NUMBER

The supplier has a choice of numerous encoding methods for the contents of the tag itself. The commonality among these methods is that they include a unique serial number. And it is the supplier's responsibility to make sure that every tag's serial number is globally unique across all materials to be shipped to any unit of the DoD.

The Advance Shipment Notice (ASN) can also be called the Receiving Report. This information is required from the shipping entity to the receiving entity or entities when products identified by RFID tags are being delivered. The exact contents of any particular ASN are specified in the detailed contract between the supplier and the DoD. In general, the ASN contains some or all of the following: