FLIS Criticality Codes & the Federal Item Identification Guide (FIIG) — Reference

The Criticality Code (CRIT CD) is a one-position code carried in the Federal Logistics Information System (FLIS) cataloging management data for a National Stock Number. It flags that an item is technically critical — by reason of tolerance, fit restrictions, application, nuclear-hardness properties, or other characteristics that affect how the item is identified — and it is the FLIS field through which Critical Safety Items (CSIs) and Aviation Critical Safety Items / Flight Safety Critical Aircraft Parts (ACSI/FSCAP) are identified. It is a distinct field from the Controlled Inventory Item Code (CIIC), which governs security, sensitivity, and pilferage controls. The closely related Federal Item Identification Guide (FIIG) is the cataloging guide that prescribes the standard requirements and format for describing and identifying an item of supply in the Federal Catalog System. Both are governed by DoD Manual 4100.39 (formerly DoD 4100.39-M), the FLIS Procedures Manual.

At a glance

• What the Criticality Code is: A one-position code in the FLIS catalog management data that flags an item as technically critical and identifies CSIs / flight-safety-critical parts.
• What it indicates: Technical criticality by reason of tolerance, fit restrictions, application, nuclear-hardness properties, or other characteristics affecting identification of the item.
• Length and format: A single alphabetic character carried in the NSN's management data.
• Regulatory source: DoD Manual 4100.39 (formerly DoD 4100.39-M), FLIS Procedures Manual; the Criticality Code values are defined in Volume 10, Table 181.
• What the FIIG is: The Federal Item Identification Guide — a cataloging handbook prescribing the standard requirements and format for identifying an item of supply by its differentiating characteristics.
• Operated by: The Defense Logistics Agency (DLA) Logistics Information Services, which runs FLIS for the Department of Defense.
• Where used: FLIS cataloging and item-identification processes; the code is visible through WebFLIS / FLIS and PUB LOG.

What the criticality code is

The Criticality Code is the FLIS catalog-management-data field that tells a logistician an item is not ordinary — that it carries a technical, safety, or nuclear-survivability sensitivity significant enough to affect how the item is identified and managed. The authoritative definition is consistent across the public reproductions of the FLIS standards: a criticality code indicates that an item is technically critical by reason of tolerance, fit restrictions, application, nuclear-hardness properties, or other characteristics which affect identification of the item.

Two threads run through that definition, and they are worth separating because the code values fall into the same two families:

• Identification-critical features — tolerance, fit restrictions, and application. When an item has these, substituting a visually similar part is not safe: the dimensional precision, the way it mates with other parts, or the specific application it was qualified for all matter to its identity. The code says, in effect, get the exact item; do not assume an apparent equivalent will do.
• Nuclear hardness — whether the item is specifically designed or selected to keep performing in the environment created by a nuclear explosion. This is a distinct kind of criticality from dimensional/fit criticality, and several code values exist precisely to distinguish "nuclear-hard" from "has other critical features" from "both."

Layered on top of these is the code's most operationally visible role: identifying Critical Safety Items. A Critical Safety Item (CSI) is a part, assembly, or support equipment whose failure could cause loss of life, permanent disability or major injury, loss of a system, or significant equipment damage; an Aviation Critical Safety Item (ACSI) — the term that replaced Flight Safety Critical Aircraft Part (FSCAP) — is the aviation subset. CSIs are identified in FLIS by the applicable criticality code, which is why this single field is a load-bearing part of the DoD's safety-of-flight and CSI management regime.

Criticality Code vs. Controlled Inventory Item Code (CIIC)

A frequent point of confusion is the difference between the Criticality Code and the Controlled Inventory Item Code (CIIC). They are separate FLIS fields answering different questions:

• The Criticality Code flags technical criticality, safety criticality, and nuclear hardness — it is about how critical the item is to identify and manage correctly.
• The CIIC addresses an item's security classification, sensitivity, and pilferage controls for storage and transportation — it is about protecting the asset, not about technical/safety criticality.

Both are carried in the FLIS catalog management data and both are defined in the Volume 10 cataloging standards, but they are different codes with different value sets. Reading the criticality code does not tell you the CIIC, and vice versa.

The Federal Item Identification Guide (FIIG)

The Federal Item Identification Guide (FIIG) is the cataloging instrument that governs how an item of supply is described and identified in the Federal Catalog System. A FIIG is a handbook that prescribes the standard requirements and format for identifying an item of supply by those characteristics necessary to differentiate it from any other item of supply. In other words, the FIIG is what turns "a pump" into a fully specified, uniquely identifiable item record: it tells the cataloguer exactly which characteristics must be captured, in what form, to pin down precisely this item and no other.

How a FIIG is built

A FIIG is organized around the characteristics that distinguish items, expressed as coded requirements:

• Item Name Code (INC) and approved item name. Cataloging begins with naming the item. The Approved Item Name is the official designation selected for an item of supply, and each is tied to an Item Name Code (INC). The DLA H6 Item Name Directory lets users look item names up by Federal Supply Class, keyword, INC, and Item Identification Guide.
• Master Requirement Codes (MRCs). Each characteristic the FIIG asks for is identified by a Master Requirement Code (MRC) — a four-position code that identifies the requirement, cross-references it across the sections and appendices of the FIIG, and supports mechanized processing and retrieval. The cataloguer answers the relevant MRCs to build the item's characteristics record.
• Applicability and format rules. The FIIG specifies which requirements apply to which approved item names and the acceptable form of each reply, so descriptions are consistent and machine-processable across the whole catalog.

The FIIG is one of a family of cataloging tools — alongside item names, the Federal Supply Classification, edit guides, and reference/drawing files — maintained to keep the characteristics portion of the Federal Catalog System consistent.

Where the FIIG sits relative to the criticality code

The FIIG and the criticality code are at different stages of the same lifecycle. The FIIG governs item identification — it is consulted when an item is named, classified, and described so that a National Stock Number can be assigned by DLA Logistics Information Services (DLIS). The criticality code is part of the management data carried for the resulting NSN. The FIIG helps establish what the item is; the criticality code is one of the things recorded about that item once it exists in FLIS.

How they're used

The criticality code and the FIIG each do distinct work inside the federal cataloging and supply systems:

• Identifying and managing CSIs. Because CSIs are identified in FLIS by the criticality code, the code is read when sourcing, procuring, and accepting safety-critical and flight-safety-critical parts. A populated criticality value signals that the item carries the additional traceability, approved-source, and quality controls that the CSI regime requires.
• Substitution and interchangeability decisions. Identification-critical values (tolerance, fit, application) warn against treating a visually similar part as interchangeable — the criticality code is one of the flags that says "exact item required."
• Nuclear-survivability management. The nuclear-hardness values mark items engineered or selected to survive a nuclear environment, so they are managed and replaced with that survivability preserved.
• Item identification and cataloging. The FIIG is used by cataloguers to describe each item completely and consistently, answering the relevant MRCs against the approved item name so the resulting NSN record uniquely identifies the item. This is the upstream process that makes the rest of the federal catalog data in WebFLIS / FLIS trustworthy.

Criticality code values

The criticality code values below are the complete set defined in DoD Manual 4100.39 (FLIS Procedures Manual), Volume 10, Table 181 — "Criticality Code, Federal Item Identification Guide." Each definition is reproduced verbatim from Table 181. Per the table's own notes, assignment of codes E, H, or M requires a specific statement on the drawing and/or technical documentation that the item is a nuclear-hardness-critical item.

Worked example

A DLA cataloguer is creating an item identification for a new aircraft fuel-system fitting. Using the Federal Item Identification Guide keyed to the item's approved name and Federal Supply Class, the cataloguer answers each applicable Master Requirement Code — material, thread form, pressure rating, end configuration, dimensional tolerances — so the resulting record uniquely differentiates this fitting from any other. That description, once approved, lets DLA Logistics Information Services assign a National Stock Number.

Downstream, an inventory manager pulls that NSN's FLIS management data and reads the Criticality Code. Suppose it shows F — the item is an Aviation Critical Safety Item / Flight Safety Critical Aircraft Part. That single character changes how the item is sourced and accepted: it must come from an approved source with full traceability, and substitution with an apparently similar fitting is not permitted. Had the field instead shown a code indicating only tolerance/fit/application criticality without CSI status, the warning would be narrower — exact-item-required, but not under the full CSI regime. Reading the criticality code, alongside the rest of the management data, is how the logistician knows which controls apply before the part ever moves.

Common errors and gotchas

• Confusing the Criticality Code with the CIIC. They are different FLIS fields. The criticality code flags technical/safety/nuclear criticality; the Controlled Inventory Item Code (CIIC) governs security, sensitivity, and pilferage controls. Reading one does not tell you the other.
• Assuming an empty or "no critical feature" code means "ignore." Some values explicitly state nuclear hardness was not determined and are not valid for input — that is a data-status statement, not a clearance to treat the item as non-critical without checking the rest of its management data.
• Treating a criticality value as a license to substitute. The whole point of identification-critical values (tolerance, fit, application) is that exact identity matters; a visually similar part is not necessarily interchangeable.
• Reading "nuclear hard" too broadly. The nuclear-hardness values are specific: they mark items designed or selected to survive a nuclear-explosion environment. They do not mean the item is otherwise critical unless the value also says so.
• Confusing the FIIG with the finished catalog record. The FIIG is the guide that tells a cataloguer how to describe an item; it is not the item's NSN record. The criticality code is a field on the record, not part of the FIIG.
• Relying on a cached value table. Criticality-code values and their wording are set in the current DoD Manual 4100.39; public reproductions can lag or be incomplete. Confirm against the live manual for authoritative values.

Related codes and cross-references

• Acquisition Advice Codes (AAC) — the FLIS management-data code for how an item is acquired and provided, read alongside the criticality code on the NSN record.
• Controlled Inventory Item Codes (CIIC) — the FLIS security/pilferage handling code on the same record; an item can be mission-critical without being a controlled item, and vice versa.
• Weapon System Designator Code (WSDC) — the weapon-system coding family whose Weapon System Essentiality Code (WSEC) is easily confused with this criticality code; they are separate FLIS fields answering different questions.
• DoD Shelf-Life Codes (SLC) — the management-data code for how long an item keeps and whether that period can be extended.
• Supply Condition Codes (SCC) — the serviceability classification of a specific quantity of material.
• Units of Issue (U/I) — how the item is requisitioned and issued; another field in the item's management data.
• WebFLIS / FLIS — the federal catalog query tool where the criticality code and the rest of an NSN's management data are visible.
• PUB LOG — the published FLIS data product carrying NSN management data.
• Defense Logistics Information Service (DLIS) — the DLA organization that assigns NSNs and maintains the FLIS catalog tools, including the FIIGs.

Authoritative references

• DoD Manual 4100.39 (formerly DoD 4100.39-M), Federal Logistics Information System (FLIS) Procedures Manual, Volume 10 — Table 181, "Criticality Code, Federal Item Identification Guide." The authoritative definition of the complete criticality-code value set (C, E, F, H, M, N, S, V, X, Y), verified verbatim against this table. The companion CIIC is Table 61 of the same volume. Published by the DoD issuances office.
• Defense Logistics Agency — Federal and International Cataloging (H6 Item Name Directory). The DLA cataloging resource for item names, INCs, and the Item Identification Guides; see the H6 page.
• Defense Acquisition University (DAU) — Critical Safety Item (CSI) reference. Defines the CSI and Aviation CSI / FSCAP terms and states that CSIs are identified in FLIS by the criticality code; see the DAU CSI reference.

Last verified

This reference was last reviewed on 2026-06-20. The complete criticality-code value set (C, E, F, H, M, N, S, V, X, Y) and the wording of every definition are verified verbatim against DoD Manual 4100.39, Volume 10, Table 181 (effective 27 Oct 2022). The table/volume numbers are confirmed from the same source: the Criticality Code is Volume 10 Table 181 and the Controlled Inventory Item Code (CIIC) is Volume 10 Table 61. The definition of the criticality code, the fact that CSIs are identified in FLIS by the criticality code, the CSI / ACSI (FSCAP) definitions, and the role and structure of the FIIG (differentiating-characteristics handbook, approved item names / INC, four-position MRCs) are corroborated across DLA, DAU, and FLIS materials. To suggest a correction, use the site's correction path.