What is an IETM?

A manual shown on a screen is not necessarily a manual that helps a technician through a repair. An Interactive Electronic Technical Manual (IETM) is a technical manual authored for an electronic display and designed to interact with its user, guiding a technician through a procedure instead of showing pages. The definition came from a U.S. tri-Service working group, and it sorts electronic manuals into classes, only some of which are IETMs. The class says what a reader can expect from a given file.

1. 0Page images, no indexNot an ETM
2. 1Electronically indexed page imagesETM
3. 2Electronic scrolling documentsETM
4. 3Linear structured IETMsIETM
5. 4Hierarchically structured IETMsIETM
6. 5Integrated database systemsIETM

The line falls between Class 2 and Class 3: an IETM has interaction authored into the content, not supplied by the viewer.

Source: Jorgensen, The Interactive Electronic Technical Manual Overview, Naval Surface Warfare Center, Carderock Division.

What sets an IETM apart

The clearest public account is a 1994 paper by Eric L. Jorgensen of the Naval Surface Warfare Center's Carderock Division, "The Interactive Electronic Technical Manual Overview: Setting the Stage". It describes an IETM as the functional equivalent of a paper technical manual and, in most cases, a total replacement for it. Three characteristics separate an IETM from paper shown on a screen:

• Formatted for the display. Less information is shown at one time, and it is more focused.
• Graphics tied to text. The specific graphic, or portion of a graphic, that goes with a statement is displayed whenever that statement is displayed. The paper calls this much more effective than a "see Figure x" reference.
• Interaction. The manual can ask the user for information and use the answer to decide what to show next, which lets it guide a user through a procedure in a way paper cannot.

The classes

The Department of Defense (DoD) issued three IETM specifications in November 1992, written for programs that could author an IETM from the start. As the paper explains, the end of the Cold War delayed many of those new programs, and the emphasis moved to converting existing manuals. The Services produced a range of conversion approaches, and the Tri-Service IETM Working Group defined classes of Electronic Technical Manuals (ETMs) to sort them:

• Class 0, page images without an index. Digitized pages kept for archive or print on demand. The paper marks this class as not an ETM.
• Class 1, electronically indexed page images. Full-page images reached through an automated index. Suited to library and reference use.
• Class 2, electronic scrolling documents. Text converted from a page-oriented document, with an index and hypertext links added but little or no re-authoring.
• Class 3, linear structured IETMs. Technical information tagged in a structured markup and displayed with a hypertext system, with navigation built by the author, including prompted dialogs and a content-driven "next" function. The source is a linear document file, not a database.
• Class 4, hierarchically structured IETMs. Information authored into and maintained in a non-redundant relational or object-oriented database, then packaged for interactive presentation under the DoD specifications.
• Class 5, integrated database systems. Class 4 IETMs integrated with data for other processes, such as expert-system rules, diagnostics, or computer-managed training. The paper leaves this class open-ended for future features.

Which classes count as IETMs

The paper gives one test. To be called an IETM, a manual must have extensive provision for interactive features put there by the author: prompts, dialogs that collect data from the user, and alternative branches the user must choose between.

By that test Classes 3 and 4 are IETMs. Class 4 fully conforms to the specifications. Class 3 has many of the same features but does not keep its source in a revisable database. To the end user the two may look equivalent, and the difference is in how the source data is managed. Class 5 is a superset of Class 4.

Classes 1 and 2 are electronic manuals without authored-in interaction. A viewer may add some interactive features of its own, but the only interaction in the file itself is, at most, a hypertext reference to another spot in the document. The distinction that matters is therefore not paper versus screen. It is whether the interaction was authored into the content or supplied by the viewing software.

Where the specifications stand now

The general IETM specification the paper describes carries the same number today, as MIL-DTL-87268. The record in ASSIST, the DoD database of specifications and standards, lists Revision D with Amendment 1, dated July 19, 2019, and shows the document's status as Inactive.

The Army-led MIL-STD-40051 was for years published in separate parts for IETMs and for page-based manuals. The current record lists Revision E, dated March 25, 2025, as a single standard for technical manuals.

S1000D takes the database approach further. The S-Series About S1000D page describes content written as stand-alone data modules, stored in a common source database, from which both page-oriented output and interactive electronic publications are produced.

What to check

A maintenance library built up over decades holds every class at once: scanned pages, converted scrolling documents, structured manuals, and database-driven publications. A scanned page offers an image and nothing else. A database-driven manual offers steps, warnings, and figures as separate, addressable things.

• Which class a vendor's IETM claim fits under the paper's definitions, whatever the manual looks like on screen.
• Whether the prompts, dialogs, and branches are authored into the content or supplied by the viewing software.
• Whether the source sits in a revisable database (Class 4) or in a linear document file (Class 3).
• Which specification a contract cites. MIL-DTL-87268 shows as Inactive in ASSIST, and MIL-STD-40051 is a single standard at Revision E.
• Whether the content is stored as stand-alone data modules in a common source database, as S1000D describes.

Azcuna's TRACE is one offline viewer for S1000D, MIL-STD-3001 XML, and PDF technical manuals. It keeps the source location and the markings of everything it shows and never modifies the source. It was proposed to NAVAIR under Navy SBIR Phase I topic DON26BZ05-NV078, and the proposal was submitted on September 23, 2026.

Sources

1. 1The Interactive Electronic Technical Manual Overview: Setting the Stage · Eric L. Jorgensen, Carderock Division, Naval Surface Warfare Center
2. 2MIL-DTL-87268, Manuals, Interactive Electronic Technical - General Content, Style, Format and User-Interaction Requirements (ASSIST record) · Defense Logistics Agency (ASSIST)
3. 3MIL-STD-40051 (ASSIST record) · Defense Logistics Agency (ASSIST)
4. 4About S1000D · S-Series IPS Specifications