MIL-STD-963 and DIDs, explained

A Data Item Description (DID) is the document that tells a defense contractor what a deliverable must contain, how it is formatted, and what the government will use it for, and MIL-STD-963 is the standard that says how a DID is written. The ASSIST-QuickSearch record kept by the Defense Logistics Agency titles MIL-STD-963 Data Item Descriptions (DIDs), shows it active at Revision C dated September 24, 2014, validated by a Notice 1 of November 7, 2019, and lists the Executive Agent for the Defense Standardization Program as preparing activity. For technical manuals the DIDs that matter carry the prefix DI-TMSS, for the technical manual specifications and standards area, and they are called out line by line on the Contract Data Requirements List (CDRL), DD Form 1423. This post explains what a DID is, how MIL-STD-963C structures and numbers one, the DI-TMSS series, how a DID ties to a CDRL, and how a program office uses DIDs to call out manual deliverables. The standards those DIDs invoke are compared in the post on the U.S. technical manual standards.

What a DID is

Paragraph 3.10 of MIL-STD-963C, hosted by EverySpec, defines a DID as "a standardization document that defines the data required of a contractor" and says it specifically defines the data content, format, and intended use. Two nearby definitions frame it. Paragraph 3.12 defines a data product as information inherently generated by work tasks cited in a statement of work or in a source document the contract invokes, treated as a separate entity such as a drawing, specification, manual, report, or parts list. Paragraph 3.21 defines a source document as a document listed in ASSIST, or a statement of work or statement of objectives, that establishes a data requirement and therefore needs a DID to define the format, content, and intended use of the data.

The line the standard draws most firmly is between data and work. Paragraph 4.3.1 says a DID shall not contain any requirement to perform work tasks such as inspection or test, shall not direct or constrain the data preparation activity, and shall not modify any contract work task; the tasks that generate the data belong in the statement of work. Paragraph 4.4.5 lists the phrases that are prohibited for that reason, among them "The contractor shall," "records shall be maintained," "data shall be submitted," and "data shall be approved by." A DID is therefore short: the two-page DI-TMSS-81814A, the Interactive Electronic Technical Manual (IETM) Content Plan, is typical.

Paragraph 1.2 divides DIDs into two classes. Repetitive-use DIDs are approved for use on contracts for more than one acquisition program and are listed in ASSIST. One-time DIDs are approved for a unique data requirement on a single contract, or on multiple contracts within one acquisition program, or when time constraints prevent preparing and approving a repetitive-use DID. Paragraph 4.1 adds the rule that keeps the library from growing without need: new DIDs shall not be prepared if an existing DID in ASSIST is adequate as is or with tailoring, and a DID shall cover a single deliverable data product, so a work task that yields two products needs two DIDs. Paragraph 4.2 allows two structures, a self-contained DID that describes the data without reference to other documents, which the standard prefers, and an abstract-reference DID that points to other documents when the volume of content makes inclusion impractical.

What MIL-STD-963C requires in a DID

Section 5 lists the data fields, shown in the standard's Figure 3. Paragraph 5.2 requires the heading DATA ITEM DESCRIPTION at the top of the first page. Paragraph 5.3 requires a title that names the data product, with acronyms only as parenthetical suffixes, as in Packaging Design Report (PDR). Paragraph 5.5 gives the approval date as an eight-digit year, month, and day, with the word Draft in the field until approval. Paragraph 5.6 covers the Acquisition Management Systems Control (AMSC) number, which paragraph 3.2 defines as a control number assigned by the ASSIST Automated Document Number Module indicating that a DID, or a specification or standard that cites DIDs, has been cleared for DoD use; it is issued with the DID number and never assigned to a one-time DID. Paragraph 5.7 records any approval limitation, or the solicitation or contract number for a one-time DID. Paragraphs 5.8 and 5.9 record whether copies go to the Defense Technical Information Center or the Government-Industry Data Exchange Program.

Paragraph 5.10 names the preparing activity by its SD-1 code, with a table of components: SO for the Office of the Secretary of Defense, AM for the Army, SA for the Navy and the Marine Corps, 10 for the Air Force, and DH for the Defense Logistics Agency, among others. Paragraph 5.11 adds a project number from the ASSIST Project Module, and 5.12 lists any forms the contractor must complete. Paragraph 5.13, Use/relationship, describes the purpose of the data and how it is used; for a DID with an ASSIST source document it carries a set sentence that the DID contains the format, content, and intended use information for the data deliverable resulting from the work task described in a named paragraph of a named document, and it lists DIDs superseded or recommended for use with it. Paragraph 5.14 holds the requirements, stated clearly, with contractor format allowed wherever possible and mandatory format reserved for interface needs such as loading a database, and paragraph 5.14.1 gives the opening sentence for any DID that cites reference documents. Paragraph 4.10 closes every DID with the words End of and the DID number.

The language rules in section 4.4 are strict. Sentences are short, "shall" marks mandatory instructions, "will" may be used for what the government will do, and "should" and "may" are avoided because DIDs normally contain only mandatory instructions. Paragraph 4.4.5 also bans "Unless otherwise specified in the contract," because every DID is approved at its maximum requirements and the only alternative is tailoring out, and bans "shall include but not be limited to" because it implies that requirements can be added in the CDRL; the paragraph states that requirements may be tailored out but additional requirements shall not be added by tailoring. Section 5.15 gives the format for a cancellation notice, which carries the DID identifier, the word Notice and a number, the approval date, and the same heading and title as the DID.

How DIDs are numbered

Paragraph 5.4.1 builds the repetitive-use number from the example DI-SESS-80013. DI means Data Item. SESS is the four-character standardization area, drawn from the Standardization Directory SD-1, which paragraph 3.13 says defines the area designations and scopes. The number 80013 is assigned by the ASSIST Automated Document Number Module when the Service or Agency DID approval authority has coordinated the DID and resolved comments. Revisions take sequential letters, and the letters I, O, Q, S, X, and Z are not used. A DID that moves to another standardization area and is revised takes the next revision letter. So DI-TMSS-80527C is the third revision of DID 80527 in the technical manual area, and its EverySpec page confirms it superseded DI-TMSS-80527B of October 17, 2006.

Paragraph 5.4.2 builds the one-time number differently: the letters OT, a dash, the two-digit fiscal year, a dash, and a five-digit number from a block the standard assigns to each component, with the Army at 10000 through 19999, the Navy at 20000 through 29999, the Air Force at 30000 through 39999, and the Office of the Secretary of Defense at 80000 through 89999. The standard's example is OT-13-10000, the first number assigned in fiscal year 2013 by the Army.

The approval authority sits in each component. Paragraph 3.11 defines the Data Item Description Approval Authority as the organization in each Military Department or Defense Agency with delegated responsibility to approve new, revised, and cancelled DIDs, listed with contact information in the SD-1. Paragraph 3.16 says approval authority is delegated by the Director of the Defense Standardization Program Office, who holds the DoD-wide responsibility for developing and implementing DoD policy for controlling and approving data requirements applied in defense contracts. Paragraph 3.3 defines ASSIST as the official database containing information about standardization documents, including DIDs, used in the DoD. The public face of that database is described on the ASSIST-QuickSearch overview, which says the site lets users search defense and federal specifications and standards, handbooks, commercial item descriptions, and data item descriptions, that it draws its metadata and files from ASSIST, and that both are updated nightly on business days.

The DI-TMSS series for technical manuals

The DIDs that call out technical manuals share the TMSS prefix with MIL-STD-40051, MIL-STD-3001, and MIL-STD-38784. EverySpec's DI-TMSS listing runs to four pages, 93 entries counting superseded revisions and notices, from DI-TMSS-80007, Test Program Manual, dated May 28, 1985, on page 1 to DI-TMSS-82312, Key Specification, dated December 18, 2019, on page 4. Page 2 is dominated by the 2006 and 2007 family of maintenance manual DIDs, DI-TMSS-81666 through 81682, covering limited, full, and depot maintenance manuals and sanitized system, subsystem, and equipment manuals, and page 3 holds the May 25, 2010 set, DI-TMSS-81810 through 81821. The main ones, with the dates EverySpec shows:

The listing pages also show DI-TMSS-81817, the Technical Manual Quality Assurance Program Plan, DI-TMSS-81820 and 81821 for verification discrepancy reports and incorporation certificates, DI-TMSS-81951 and 81952 of October 23, 2013 for the S1000D business rules decision table and the business rules exchange file, and DI-TMSS-82221, Technical Publications Report, of June 5, 2018. The business rules exchange file is explained in the post on what a BREX data module is.

The texts show how a DID sequences a manual program. DI-TMSS-81810 gives the program manager an overview of planned manual development for a ship or a major system and is submitted for review and acceptance before the manuals are developed. DI-TMSS-81813A, the Book Plan for linear page-based manuals, and DI-TMSS-81814A, the IETM Content Plan for non-linear IETMs, are each submitted before development; both are written for manuals developed under contract requirements based on MIL-DTL-24784 or S1000D tailored for Naval Sea Systems Command use, and both ask for a text outline, an illustration plan, and a table plan. The IETM plan adds the data module and publication module codes when S1000D is used. DI-TMSS-81812 reports schedule and status so the program manager can act on slippage. DI-TMSS-81818 describes the contractor's validation methods and is paired with DI-TMSS-81819A, the certificate by which the contractor attests that the manual is accurate and complete. DI-TMSS-80527C covers sample, evaluated, and accepted commercial manuals under MIL-PRF-32216. DI-TMSS-81784A says it and MIL-STD-3031 are used together to document Army project business rules for S1000D, and DI-TMSS-81805A initiates data module templates in the Navy's common source database.

The header of DI-TMSS-81814A shows the fields of section 5 as they appear in practice: Title, Number, Approval Date 20140206, AMSC Number N9451, Limitation N/A, DTIC Applicable N/A, GIDEP Applicable N/A, Office of Primary Responsibility SA/N00AL2, Applicable Forms N/A, Use/relationship, Requirements, and the closing End of DI-TMSS-81814A. The sample repetitive-use DID in the standard's own Figure 1 is also a technical manual DID, DI-TMSS-8XXX4, Technical Manual Research and Analysis Source Data.

How a DID ties to the CDRL on DD Form 1423

Paragraph 3.6 of MIL-STD-963C defines the CDRL, DD Form 1423, as the standard format for identifying potential data requirements in a solicitation and deliverable data items in a contract. Paragraph 3.8 defines a contractual data requirement as a requirement for contractor-prepared data applied by the terms of a contract. The CDRL is the list; the DID is what each line on the list points to. Paragraph 6.3 of the standard applies the rule to itself: MIL-STD-963 has an AMSC number authorizing it as the source document for DI-MISC-80000, Data Item Descriptions (DIDs), and when that data is needed the DID must be listed on the DD Form 1423 except where the DoD Federal Acquisition Regulation Supplement exempts the form. The same paragraph says the ASSIST database should be researched so that only current and approved DIDs are cited on the form.

The regulation that puts the form in the contract is DFARS 215.470, Estimated data prices. Paragraph (a) says the DoD requires estimates of the prices of data so it can evaluate what the data costs the government relative to its management, product, or engineering value. Paragraph (b) says that when data are required to be delivered under a contract, the solicitation shall include DD Form 1423, Contract Data Requirements List, with guidance on the form in PGI 215.470(b). Paragraph (c) requires the contracting officer to make sure the contract does not require data the contractor has already delivered or must deliver under another contract, and says that where duplicate data is wanted the price covers duplication but not preparation. DFARS Subpart 204.71, the uniform contract line item numbering system, places the form in the contract structure: 204.7101 defines an exhibit as a document that establishes requirements for deliverables and an attachment as documentation that does not, and states that the DD Form 1423 is always an exhibit, rather than an attachment, while 204.7103-1(d) allows an exhibit to replace a long list of contract line items, cited from a line item by its identifier. Those are the codified sections. For DoD contracting officers, class deviation 2026-O0043, issued February 3, 2026 and effective February 17, 2026 under the Revolutionary FAR Overhaul, replaces DFARS Part 204 with a deviation text in which subpart 204.71 is Reserved. The exhibit and attachment definitions and the sentence that the DD Form 1423 is always an exhibit now sit in DFARS 204.202-70, which also says to use exhibits to separately identify data deliverables on a DD Form 1423, and the long-list alternative moved to PGI 204.202-70(d). Class deviation 2026-O0048 Revision 1 of July 22, 2026, which replaces DFARS Part 215, keeps section 215.470 under the same number with the same three paragraphs.

Tailoring happens on the form. Paragraph 3.22 of MIL-STD-963C defines tailoring of data requirements as the deletion of the applicability of a portion of the data requirements from an approved DID that are unnecessary for a specific contract. Paragraph 4.3.4 requires DIDs to be structured so that tailoring is possible, with every paragraph of format and content instruction numbered or lettered, and says tailoring is normally done by referencing those paragraph identifiers in Block 16 of the CDRL for deletion or application. Because the prohibited-terms rule forbids adding requirements by tailoring, the standard leaves a program office that wants more than an approved DID provides with a new or one-time DID, not extra requirements written into the CDRL.

How a program office calls out a manual

Put together, the pieces give a sequence. The statement of work or the invoked standard creates the work task, such as developing a maintenance manual to MIL-STD-40051 or MIL-STD-3001, and MIL-STD-963C paragraph 3.21 says that document is the source document that establishes the data requirement. The program office searches ASSIST for a repetitive-use DID that describes the product, as paragraph 4.1 requires before any new DID is written, and selects one DID per deliverable data product. For a manual program that might be a plan DID before development, a schedule and status report during it, the manual DID itself, and a validation plan and certificate at the end, each on its own CDRL line. The DID number goes on the DD Form 1423 as the authority for the line, the requirements the program does not need are deleted by paragraph number in Block 16, and the form is included in the solicitation under DFARS 215.470 as an exhibit under DFARS 204.202-70 of the 2026 class deviation (204.7101 in the codified text).

If no approved DID fits, the office prepares one under MIL-STD-963C and sends it to its component's DID approval authority, which paragraphs 5.4.1, 5.5, and 5.6 say assigns the number through the ASSIST Automated Document Number Module, the approval date, and the AMSC number, or assigns a one-time OT number under paragraph 5.4.2. Paragraph 6.4 adds that when a solicitation asks the contractor to prepare DIDs, it should state whether they are repetitive-use or one-time, who the preparing activity is, and whether DTIC and GIDEP apply. The DID does not say which standard the manual is written to; that comes from the source document and the Technical Manual Contract Requirement, so the CDRL line, the DID, and the standard have to be read together to know what the government has bought.

What to check

• Does every data deliverable on the CDRL cite one approved DID by number, and is that DID current in ASSIST rather than superseded, as the revision letter on the EverySpec listing or the ASSIST record shows?
• Does Block 16 of the DD Form 1423 only delete DID paragraphs by identifier, or does it try to add requirements that MIL-STD-963C says cannot be added by tailoring?
• Does the DID carry an AMSC number and an approval date, or is it a one-time OT number limited to this contract or program?
• Which source document creates the work task behind the DID, and does the Technical Manual Contract Requirement name the standard the manual is written to?
• For a manual program, are the plan, status report, manual, validation plan, and validation certificate each on separate CDRL lines with their own DIDs, as the single-product rule of paragraph 4.1 requires?
• Is the DD Form 1423 included in the solicitation as an exhibit, as DFARS 215.470 and 204.202-70 (204.7101 in the codified text) require, with a price estimate for each data item?

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Questions people ask

What is a DID?

A Data Item Description is a standardization document that defines the data a contractor must deliver. MIL-STD-963C paragraph 3.10 says it specifically defines the data content, format, and intended use. A DID does not task the contractor to do work; paragraph 4.3.1 says work tasks belong in the statement of work. Each DID covers a single deliverable data product, and the contract calls it out by number on the Contract Data Requirements List, DD Form 1423.

What is MIL-STD-963?

MIL-STD-963 is the Department of Defense standard practice titled Data Item Descriptions (DIDs). Paragraph 1.1 of Revision C says it establishes format and content requirements for new and revised DIDs prepared by DoD activities or by contractors for use in defense contracts, and for DID cancellation notices. The ASSIST record lists the Executive Agent for the Defense Standardization Program as preparing activity, the STDZ standardization area, and status Active.

What is the current revision of MIL-STD-963?

Revision C, dated September 24, 2014, 26 pages, validated by a Revision C Notice 1 dated November 7, 2019. The ASSIST record lists the base document of March 18, 1985, Revision A of August 15, 1986, Revision B of August 31, 1997, and Revision C, which superseded Revision B. The record shows a next review date of November 5, 2024, which had passed when the record was checked, and the status remains Active.

What does a DID number mean?

MIL-STD-963C paragraph 5.4.1 gives the construction using DI-SESS-80013 as the example: DI means Data Item, SESS is the four-character standardization area from the Standardization Directory SD-1, and 80013 is assigned by the ASSIST Automated Document Number Module. Revisions take sequential letters, skipping I, O, Q, S, X, and Z, so DI-TMSS-80527C is the third revision of DID 80527 in the technical manual area. One-time DIDs instead begin OT, the fiscal year, and a number from a block assigned to each component.

What is DI-TMSS?

DI-TMSS is the prefix for Data Item Descriptions in the TMSS standardization area, technical manual specifications and standards, the same area that holds MIL-STD-40051, MIL-STD-3001, and MIL-STD-38784. EverySpec lists 93 entries across four pages, counting revisions and notices, from DI-TMSS-80007, Test Program Manual, dated May 28, 1985, to DI-TMSS-82312, Key Specification, dated December 18, 2019. The series includes manual plans, validation plans and certificates, COTS manual DIDs, and S1000D business rules.

How does a DID relate to a CDRL?

The Contract Data Requirements List, DD Form 1423, is the contract exhibit that lists every data deliverable, and each line cites one DID as its authority. MIL-STD-963C paragraph 3.6 defines the CDRL as the standard format for identifying data requirements in a solicitation and deliverable data items in a contract. Codified DFARS 204.7101 says the DD Form 1423 is always an exhibit rather than an attachment; class deviation 2026-O0043, effective February 17, 2026, reserves subpart 204.71 and moves that sentence to DFARS 204.202-70. DFARS 215.470 requires the form in any solicitation that requires data delivery.

Can a DID be tailored?

Only by deletion. MIL-STD-963C paragraph 3.22 defines tailoring as deleting the applicability of portions of an approved DID that a contract does not need, and paragraph 4.3.4 says this is done by citing paragraph identifiers in Block 16 of the CDRL. Paragraph 4.4.5 prohibits phrases such as shall include but not be limited to because they imply requirements can be added, and states that requirements may be tailored out but additional requirements shall not be added by tailoring.

What is a one-time DID?

MIL-STD-963C paragraph 1.2 defines a one-time DID as one approved for a unique data requirement on a single contract, or on several contracts in one acquisition program, or when time does not allow a repetitive-use DID to be approved. Paragraph 5.4.2 numbers them OT, a dash, the two-digit fiscal year, a dash, and a five-digit number from a block assigned to each component, with Army at 10000 through 19999 and Navy at 20000 through 29999. One-time DIDs get no AMSC number.

What is an AMSC number on a DID?

MIL-STD-963C paragraph 3.2 defines the Acquisition Management Systems Control number as a control number assigned by the ASSIST Automated Document Number Module indicating that a DID, or a specification or standard that cites DIDs, has been cleared for use by the DoD. Paragraph 5.6 says the AMSC number is issued with the DID number for repetitive-use DIDs and not assigned to one-time DIDs. DI-TMSS-81814A, for example, carries AMSC number N9451.

Where do I find current DIDs?

In ASSIST, the Defense Logistics Agency database that MIL-STD-963C paragraph 3.3 calls the official source of information about standardization documents including DIDs. The public ASSIST-QuickSearch site indexes data item descriptions along with specifications, standards, and handbooks, draws its metadata and files from ASSIST, and is updated nightly on business days. Paragraph 6.3 of the standard says the ASSIST database should be researched so that only current and approved DIDs are cited on the DD Form 1423.

Sources

1. 1MIL-STD-963, Data Item Descriptions (DIDs) (ASSIST-QuickSearch Document Details) · Defense Logistics Agency, ASSIST-QuickSearch
2. 2MIL-STD-963C, Department of Defense Standard Practice: Data Item Descriptions (DIDs) · Department of Defense, September 24, 2014, via EverySpec
3. 3ASSIST-QuickSearch Overview · Defense Logistics Agency, ASSIST-QuickSearch
4. 4DFARS Subpart 215.4, Contract Pricing (215.470 Estimated data prices) · Defense Acquisition Regulations System, Acquisition.gov
5. 5DFARS Subpart 204.71, Uniform Contract Line Item Numbering System · Defense Acquisition Regulations System, Acquisition.gov
6. 6DFARS Revolutionary FAR Overhaul Class Deviations (2026-O0043, DFARS Part 204; 2026-O0048 Revision 1, DFARS Part 215) · Defense Pricing, Contracting, and Acquisition Policy, Defense Acquisition Regulations System
7. 7DI-TMSS, Data Item Descriptions, listing page 1 · EverySpec
8. 8DI-TMSS, Data Item Descriptions, listing page 2 · EverySpec
9. 9DI-TMSS, Data Item Descriptions, listing page 3 · EverySpec
10. 10DI-TMSS, Data Item Descriptions, listing page 4 · EverySpec
11. 11DI-TMSS-81814A, Data Item Description: Interactive Electronic Technical Manual (IETM) Content Plan · Department of the Navy, February 6, 2014, via EverySpec
12. 12DI-TMSS-81813A, Data Item Description: Technical Manual Book Plan · Department of the Navy, February 6, 2014, via EverySpec
13. 13DI-TMSS-81810, Data Item Description: Technical Manual Organization Plan (TMOP) · Department of Defense, May 25, 2010, via EverySpec
14. 14DI-TMSS-81812, Data Item Description: Technical Manual Schedule and Status Report · Department of Defense, May 25, 2010, via EverySpec
15. 15DI-TMSS-81818, Data Item Description: Technical Manual Validation Plan · Department of Defense, May 25, 2010, via EverySpec
16. 16DI-TMSS-81819A, Data Item Description: Technical Manual Validation Certificate · Department of Defense, November 8, 2011, via EverySpec
17. 17DI-TMSS-80527C, Data Item Description: Commercial Off-the-Shelf (COTS) Manuals and Associated Supplemental Data · Department of Defense, August 12, 2011, via EverySpec
18. 18DI-TMSS-81784A, Data Item Description: Army S1000D Project Business Rules · Department of the Army, April 19, 2011, via EverySpec
19. 19DI-TMSS-81805A, Data Item Description: Data Module Requirements List (S1000D) · Department of the Navy, November 16, 2020, via EverySpec
20. 20DI-TMSS-82180, Data Item Description: Nondestructive Inspection (NDI) Procedures Technical Manual · Department of Defense, March 7, 2018, via EverySpec

Where this shows up in our work

• TRACE, the offline S1000D and IETM viewer opens S1000D, MIL-STD-3001 and PDF technical manuals on a tablet with every marking intact.
• ELLMENT, the offline LLM for E-2D crews answers a crew's question from the aircraft's own manuals and cites the page, with no network.