Glossary of government parts purchasing terms

This glossary defines 38 terms you will meet when you look up a national stock number, read a DLA solicitation or register to sell to the government. Each entry has its own link, so you can point to one term directly.

A

Acquisition Method Code (AMC)

A one-digit code (0 to 5) recording how the Department of Defense plans to buy a spare part: competitively, from the actual manufacturer, or from a sole source. See AMC and AMSC codes.

Acquisition Method Suffix Code (AMSC)

A one-letter code that explains the reason behind a part's AMC, such as who owns the technical data. Only AMSC G implies full and open competition. See AMC and AMSC codes.

Approved source

A supplier the government has named or accepted as a source for an item. DIBBS lets you search by approved part number or approved CAGE, and some AMSC values limit buying to approved or qualified sources.

Award

The outcome of a solicitation: the contract or order the government places with the chosen supplier. DIBBS shows awards, and NSN Explorer builds price history from them.

B

Breakout

In the DoD spare parts program, moving a part away from single-source buying toward competition or direct purchase from the actual manufacturer. A technical review called screening decides what is possible.

C

CAGE code

Commercial and Government Entity code. A five-character identifier for a business facility that deals with the government, assigned by DLA. See what is a CAGE code.

Contracting officer

A government employee with authority to enter into, administer or end contracts and to make related decisions, within the limits of the authority delegated to them.

D

DIBBS

The DLA Internet Bid Board System, where vendors search for DLA solicitations and awards and submit quotes. See how to bid on DIBBS.

DLA

The Defense Logistics Agency. It manages the defense supply chain from raw materials to disposal and buys and distributes goods for the military services and other customers.

F

Federal Logistics Information System (FLIS)

The government's catalog of NSN and cataloging data, managed by DLA Logistics Information Services. DLA says it holds more than 7 million active NSNs.

Federal Supply Class (FSC)

The first four digits of an NSN. It groups similar items, for example 5310 for nuts and washers. See FSC explained.

Federal Supply Group (FSG)

The first two digits of an NSN. It is the broad category that holds a number of classes, for example 84 for clothing.

Full and open competition

A contract action in which all responsible sources are permitted to compete, as the FAR defines it.

I

Invitation for bid (IFB)

A solicitation for sealed bids. Under the FAR, replies to an invitation for bid are called bids.

N

NAICS code

North American Industry Classification System code. It classifies a business by industry and is used by federal statistical agencies. SAM.gov registration asks which NAICS codes apply to your business.

NCAGE code

The NATO version of the CAGE code, used for entities outside the United States. SAM.gov says non-U.S. entities must request one before starting a registration.

NCB code

National codification bureau code. The two digits after the supply class in an NSN, showing which country assigned it. DLA lists 00 and 01 for the United States.

NIIN

National Item Identification Number. The last nine digits of an NSN: the country code plus the seven-digit item number. See what is an NSN.

Nomenclature

The common name of an item. DIBBS lets you search solicitations by nomenclature.

NSN

National Stock Number. A 13-digit code that identifies one item in the federal supply system: a 4-digit class, a 2-digit country code and a 7-digit item number. See what is an NSN.

P

Part number

The identifier a manufacturer or other source uses for its own product. An NSN record lists known part numbers with the CAGE codes of their sources.

PIID

Procurement instrument identifier. A unique identifier of 13 to 17 letters and digits that agencies assign to each solicitation, contract, order and similar instrument. It stays unique across the government.

PSC (Product and Service Code)

A code on federal contract records that describes what was bought. The PSC Manual says the code is based on the predominant product or service in the action. It is separate from the FSC and from NAICS.

PUB LOG

DLA's free public logistics data product. It includes searchable NSN records and cross-references between NSNs, part numbers and CAGE codes, and it is updated monthly.

Q

Qualified products list (QPL)

A list of products or sources that have met qualification requirements. When an item falls under QPL procedures, competition is limited to listed or qualifiable sources. DIBBS can flag QPL items.

Quotation

A supplier's reply to a request for quotation. The FAR says that in simplified acquisition the replies are quotations rather than offers.

R

Replenishment parts

Repairable or consumable parts bought after the initial provisioning process. DFARS subpart 217.75 sets the rules that apply to them.

Request for proposal (RFP)

A solicitation where replies are called proposals. A DLA briefing says RFPs appear on DIBBS but are answered with an uploaded proposal rather than the quote form.

Request for quotation (RFQ)

A solicitation that asks suppliers to quote a price and delivery for an item. On DIBBS, RFQs can be searched by class, NSN, solicitation number and more.

S

SAM.gov

The System for Award Management, the government's platform for doing business with federal agencies. Registration is free, issues your UEI, and must be renewed every 365 days.

Set-aside

A purchase reserved exclusively for small business concerns. Some set-asides are open to all small businesses and others are limited to groups such as 8(a), HUBZone, service-disabled veteran-owned, women-owned or small disadvantaged businesses.

Small business concern

An independently owned and operated firm, with its affiliates, that is not dominant in its field and meets the Small Business Administration's size standards.

Sole source

Buying from only one supplier. The FAR lets an agency skip full and open competition when only one responsible source can meet the need, with written justification and approval. In DoD spare parts codes, AMC 3, 4 and 5 point to single-source buying.

Solicitation

The government's published request for suppliers to offer to sell something. On DIBBS the main kinds are RFQs, RFPs and IFBs, and each has a solicitation number.

U

Unique Entity ID (UEI)

The identifier for doing business with the federal government. SAM.gov generates it. GSA says the DUNS number has been removed and is no longer valid for identifying federal awards. The UEI is separate from the CAGE code.

Unit of issue

The unit in which an item is issued, such as EA for each. A unit pack of 25 nuts with a unit of issue of EA is labeled 25 EA.

USAspending

The public website where federal agencies report spending data under the DATA Act. It covers contract and grant awards, with contract data drawn from the Federal Procurement Data System.

W

WebFLIS

DLA's web interface to FLIS data, which DLA says is updated several times a day. The same cataloging data is available free through PUB LOG.

On NSN Explorer

Try the terms on live records. Look up an item from the home page, browse the catalog of supply classes, or see what is open for bid at Open demand. The methodology page explains where each figure comes from.

Common questions

What is the difference between an NSN and a NIIN?

An NSN is the full 13-digit national stock number. The NIIN is its last nine digits, the country code plus the item number, without the 4-digit supply class.

What is the difference between an RFQ and an RFP?

An RFQ asks suppliers for a quotation, and an RFP asks for proposals. The FAR says that replies to requests for quotations under simplified acquisition are quotations, while negotiated replies are proposals.

How are SAM.gov, the UEI and the CAGE code related?

SAM.gov is the registration system. Registering gives a company a Unique Entity ID, and a U.S. company without a CAGE code is assigned one through the registration. The UEI and the CAGE code are separate identifiers.

Sources

Official pages used for this guide. Rules and web pages change, so check them before you act.

Keep reading

This guide describes how the system works and points to the official instructions. It is general information, not legal advice, and it does not recommend bidding on anything. NSN Explorer is an independent site and is not affiliated with the U.S. government.

Last reviewed October 2026.