Written and maintained by CASRAI Editorial Board
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IEEE keywords, formally labeled as Index Terms in IEEE publications, are controlled descriptors assigned to a manuscript to enable bibliographic indexing, automated reviewer assignment, and discovery across the IEEE Xplore digital library. In electrical engineering, microelectronics, and signal processing, accurate keyword selection ensures that published work reaches the appropriate specialist audience and is correctly classified in international citation databases.
Purpose of the Section
The index terms section serves three distinct technical functions within the IEEE publishing workflow:
- Database Indexing and Retrieval: IEEE Xplore, Elsevier Scopus, and Clarivate Web of Science ingest author-assigned keywords to power subject-specific queries, faceted filtering, and citation graph mapping.
- Automated Reviewer Matching: During editorial triage, IEEE manuscript tracking portals match submitted index terms against reviewer profile taxonomies to recommend qualified Associate Editors and independent referees under single-anonymous or IEEE double-blind peer review workflows.
- Topical Disambiguation: Controlled vocabulary eliminates ambiguity between overlapping abbreviations and engineering subfields (for example, distinguishing between analog integrated circuits and digital signal processor architecture).
Structure (Ordered List)
Selecting and formatting IEEE keywords follows a five-step hierarchy based on official IEEE classification tools:
- Consult the IEEE Taxonomy First: Begin by consulting the current IEEE Taxonomy (Version 1.05, released January 2025). The taxonomy is a hierarchical subset derived from the top three levels of the broader IEEE Thesaurus, organized alphabetically by primary term-families (such as Circuits and systems, Semiconductor devices, or Power engineering) with up to three indented sublevels.
- Check the Comprehensive IEEE Thesaurus: If the primary taxonomy lacks the granular descriptor for your subdiscipline, search the full IEEE Thesaurus. The thesaurus contains over 12,000 controlled technical terms and specifies formal relational indicators, including Broader Terms (BT), Narrower Terms (NT), Related Terms (RT), and USE references that redirect obsolete synonyms to approved preferred terms.
- Select Between 4 and 8 Terms: Balance your keyword list across multiple abstraction tiers:
- 1–2 broad discipline terms establishing the general domain (e.g., Integrated circuits, Power electronics);
- 2–4 specific technical terms capturing the methodology, circuit architecture, or physical phenomena (e.g., Phase-locked loops, Wide-bandgap semiconductors, Gallium nitride);
- 1 application or target outcome descriptor (e.g., Radar detection, Energy efficiency).
- Order the Terms Alphabetically: IEEE formatting rules require that keywords be listed in strict alphabetical order rather than by order of importance or appearance in the manuscript text.
- Apply IEEE Typography Rules: Place the keywords immediately below the abstract. In Microsoft Word templates, use the bold lead-in Index Terms— followed by the alphabetical list separated by commas, ending with a period. In LaTeX documents using the standard
IEEEtran.clsdocument class, enclose the terms inside thebegin{IEEEkeywords} ... end{IEEEkeywords}environment. Capitalize the first letter of each keyword, maintaining uppercase formatting only for established engineering acronyms (e.g., CMOS, MOSFET, FPGA).
A Short Annotated Example
Consider a manuscript detailing a high-efficiency gallium nitride power converter for electric vehicle battery systems. The keywords are selected and formatted as follows:
Index Terms—Electric vehicles, Gallium nitride, Power conversion, Power MOSFET, Pulse width modulation, Silicon carbide, Wide-bandgap semiconductors.
Annotation of Selection Logic:
- Electric vehicles: High-level application domain term verified in the IEEE Taxonomy under Transportation and Power engineering.
- Gallium nitride: Specific semiconductor material term verified in the IEEE Thesaurus under Semiconductor materials.
- Power conversion: Functional subfield descriptor linking the study to IEEE Power Electronics Society index clusters.
- Power MOSFET: Controlled component term found at Level 3 of the Circuits and systems branch in the January 2025 IEEE Taxonomy.
- Pulse width modulation: Specific modulation control technique matching standard indexing descriptors.
- Silicon carbide: Benchmark comparison material, aiding comparative searches on wide-bandgap performance.
- Wide-bandgap semiconductors: Broader material category ensuring inclusion in macro-level semiconductor review searches.
Common Mistakes
Editorial offices frequently return manuscripts during initial formatting triage due to basic keyword errors:
| Common Mistake | Why It Impairs Indexing | Correct IEEE Practice |
|---|---|---|
| Inventing uncontrolled buzzwords | Free-text phrases not in the IEEE Thesaurus fail automated keyword matching. | Select established descriptors directly from the IEEE Taxonomy or Thesaurus. |
| Listing terms non-alphabetically | Violates the IEEE style guide and requires manual correction in page proofs. | Sort all index terms in strict alphabetical order before submission. |
| Using fewer than 3 or more than 10 terms | Too few terms cause search invisibility; too many dilute topical specificity. | Provide between 4 and 8 precisely targeted index terms. |
| Duplicating the entire paper title | Redundant words waste indexing capacity without adding search value. | Choose complementary terms that expand discovery beyond title keywords. |
| Punctuation errors in lead-in | Incorrect dashes or hyphens disrupt template macros. | Use an em dash (—) immediately following “Index Terms” without a trailing hyphen. |
Checklist
Before uploading your final manuscript to the IEEE author submission portal, verify each requirement:
- [ ] Every chosen keyword exists as a verified term in the IEEE Taxonomy (v1.05) or IEEE Thesaurus.
- [ ] The list contains between 4 and 8 distinct terms.
- [ ] All terms are sorted in strict alphabetical order (A to Z).
- [ ] The lead-in reads Index Terms— (or is enclosed in
begin{IEEEkeywords}in LaTeX). - [ ] The first letter of each term is capitalized, with all standard acronyms fully capitalized.
- [ ] Terms are separated by commas (or semicolons if specified by the society transaction) and terminate with a final period.
- [ ] Citations in the body follow standard IEEE reference format.
Discipline Differences
While IEEE enforces standardized formatting across all societies, indexing systems differ across professional technical organizations:
- Computer Science (ACM vs. IEEE): While IEEE uses the unified IEEE Taxonomy and Thesaurus across both hardware and software, the Association for Computing Machinery mandates the ACM CCS concepts XML taxonomy for computer science conferences, which requires generating poly-hierarchical XML code blocks rather than a simple comma-separated list.
- Biomedical Engineering (IEEE EMBS): Authors submitting to the IEEE Transactions on Biomedical Engineering or IEEE Open Journal of Engineering in Medicine and Biology frequently pair controlled IEEE Thesaurus terms with Medical Subject Headings (MeSH) to optimize discoverability on PubMed and MEDLINE.
- Geoscience and Remote Sensing (IEEE GRSS): Manuscripts often incorporate specialized earth observation satellite mission terms (e.g., Earth Observing System, Synthetic aperture radar) directly listed under the Aerospace and electronic systems branch of the taxonomy.
Frequently Asked Questions
What is the difference between the IEEE Taxonomy and the IEEE Thesaurus?
The IEEE Thesaurus is the master controlled vocabulary containing over 12,000 terms with cross-referenced Broader Terms, Narrower Terms, and Related Terms. The IEEE Taxonomy is an 80-page hierarchical subset derived from the top three hierarchical levels of the thesaurus, organized into alphabetical term-families with up to three sublevels.
Can authors suggest new keywords not in the IEEE Thesaurus?
Yes. If your research introduces an emerging technology or novel material not yet represented in the controlled vocabulary, you may include an author-defined keyword. IEEE indexers review novel author keywords during cataloging and propose them for inclusion in future annual updates of the IEEE Thesaurus.
Are IEEE keywords required for conference proceedings?
Most IEEE conferences require 3 to 5 index terms on the title page to facilitate conference technical program scheduling and session grouping. Always consult the specific conference call-for-papers author kit for exact length limits.
Sources
- Institute of Electrical and Electronics Engineers (IEEE), IEEE Taxonomy Version 1.05, Hierarchical Display of IEEE Thesaurus Terms, January 2025. https://raw.githubusercontent.com/angelosalatino/ieee-taxonomy-thesaurus-rdf/main/source/ieee-taxonomy-2025.pdf
- Institute of Electrical and Electronics Engineers (IEEE), IEEE Editorial Style Manual for Authors, Publication Guidelines, 2025. https://www.ieee.org/content/dam/ieee-org/ieee/web/org/pubs/style_manual.pdf
- Open University / Knowledge Media Institute, IEEE Taxonomy and Thesaurus Semantic Mapping Dataset, 2025. https://github.com/angelosalatino/ieee-taxonomy-thesaurus-rdf
