Two OJS features that look almost identical — but structure your journal in completely different ways. Here’s what Sections and Categories each really do, and why a section sometimes refuses to be deleted.

If you manage a journal in Open Journal Systems (OJS), sooner or later you run into two features that look like they do the same thing — Sections and Categories — and a frustrating moment where OJS refuses to delete a section, insisting “someone is still using it,” even though you’re sure no article does.

Both problems come from the same misunderstanding. Once you understand what each feature actually is, everything falls into place: your Table of Contents gets cleaner, your indexing gets more reliable, and readers get a genuinely useful way to browse your journal.

This guide clears it up with plain language and five real-world examples.

The short answer

If you remember only one line: **a Section says what kind of article this is; a Category says what it’s about.**

What a Section really is

A Section is the structural building block of an issue. When you open any issue’s Table of Contents, the headings you see — “Research Articles,” “Reviews,” “Editorial” — are sections.

Key properties:

• One section per submission. During submission, an article is placed in a single section. It cannot live in two sections at once.
• It structures the Table of Contents. Sections group and order the articles within an issue.
• It carries editorial rules. A section defines whether items are peer-reviewed, whether an abstract is required, word limits, section policy, and which section editors handle it.
• It travels with the record. The section is part of your issue structure and is carried through your journal’s OAI-PMH feeds and native XML exports, which is how harvesters and indexes read your content’s structure.

Technically, a section is simply the single main editorial division a submission is attached to — OJS itself doesn’t force it to mean “type,” and some journals legitimately use sections for a discipline, a standing theme, or a special collection. But because a section maps so naturally onto article type, that’s how the overwhelming majority of well-run journals use it:

Research Article · Review Article · Case Report · Short Communication · Editorial · Letter to the Editor · Book Review

A note worth making: some journals create a single generic section called simply “Articles” and drop everything into it. OJS will let you do this, but it’s not ideal — indexers and readers still want to know the article type. If you go this route, make sure the article type is clearly stated inside the PDF (e.g., a “Research Article” label on the first page). Article type is one of the things indexes and reviewers check most often, so it should be clearly stated somewhere the reader can see it — even if the exact requirement varies from one standard to the next.

And this isn’t only house style. Publishing standards such as JATS XML (used by PubMed Central and many indexing services) formally enumerate article types — research-article, review-article, case-report, editorial, letter, and so on — through a dedicated article-type attribute. Keeping your sections aligned with these recognized types makes your exported metadata cleaner and more machine-readable downstream.

(For a deeper look at article types, see our companion guide: Types of Articles in Academic Publishing — A Comprehensive Guide.)

What a Category really is

A Category is a completely different animal. It is not a property of the article in the bibliographic sense — it’s a browsing and listing tool for readers.

Key properties:

• A subject/topic layer. Categories organize your articles into thematic collections (“Cardiology,” “Public Health,” “Renewable Energy”).
• Multiple categories per article. A single article about, say, air pollution and childhood asthma can sit in both “Environmental Health” and “Pediatrics” at the same time.
• Journal-wide, not issue-bound. When a reader clicks a category, OJS lists every article in that topic — no matter which issue or year it was published in.
• It has its own page and a browse block. Each category gets a dedicated page listing its articles; you can also enable a “Browse by Category” block in the sidebar so readers can explore topics directly.
• It appears on the article landing page, linking readers to related articles — but it does not appear in the issue’s Table of Contents, and it normally does not appear in the PDF.
• It can be nested. Categories support one level of parent/child hierarchy (e.g., “Clinical Medicine” → “Cardiology”), which sections cannot do.

In other words: sections describe this article, in this issue; categories describe a theme, across the entire journal.

Why OJS won’t let you delete a section

Here’s the scenario that starts most of these conversations:

“I want to delete a section, but OJS says someone is using it. But not all my articles use it — so why won’t it let me?”

The rule is stricter than people expect: **OJS blocks deletion if even one submission is still assigned to the section. “Most articles don’t use it” isn’t enough — you need zero** submissions attached.

And the culprit is usually a submission you weren’t thinking about:

• an old article sitting in a back issue,
• a declined or archived submission (these still count),
• or an incomplete draft parked in the submission queue.

Do not force the deletion. If a section is removed while submissions are still attached to it, OJS can orphan those submissions — their section link becomes empty, and they can disappear from the interface entirely. That’s a data-integrity problem you don’t want.

The safe procedure:

1. Find every submission still assigned to the section. Check all issues (including back issues), the active queue, and the Archives (declined/incomplete included).
2. Open each one → Publication tab → reassign it to the correct section.
3. When the count reaches zero, OJS will let you delete the section cleanly.
4. Prefer to keep history intact? Deactivate the section instead of deleting it. It stays valid for already-published articles but stops accepting new submissions.

Five example journals: same sections, different categories

Here’s the pattern that makes everything click. Notice that the Sections (article types) stay almost identical from journal to journal — because article types are universal. What changes journal to journal is the Categories, because subjects are specific to each journal’s field.

1. A general medical journal

• Sections (types): Research Article · Review Article · Case Report · Clinical Image · Editorial · Letter to the Editor
• Categories (subjects): Cardiology · Oncology · Neurology · Infectious Diseases · Public Health · Pharmacology

A single case report on a heart-drug interaction could sit in both “Cardiology” and “Pharmacology” categories — while its section stays simply “Case Report.”

2. An environmental science journal

• Sections (types): Research Article · Review Article · Short Communication · Perspective · Editorial
• Categories (subjects): Climate Change · Biodiversity & Conservation · Water Resources · Renewable Energy · Pollution & Waste · Environmental Policy

A reader clicking “Renewable Energy” sees every relevant article from 2019 to today, whether it was a full research article or a two-page short communication.

3. An education journal

• Sections (types): Research Article · Review Article · Case Study · Book Review · Editorial
• Categories (subjects): Early Childhood Education · Higher Education · Educational Technology · Assessment & Measurement · Teacher Training · Inclusive Education

“Educational Technology” and “Higher Education” can both be tagged on one article about online learning in universities.

4. A business & management journal

• Sections (types): Research Article · Review Article · Case Study · Viewpoint · Editorial
• Categories (subjects): Marketing · Finance & Accounting · Human Resources · Entrepreneurship · Operations & Supply Chain · Strategy

Categories double as a de facto “explore by discipline” menu for readers who don’t care which issue an article appeared in.

5. A multidisciplinary / sustainability journal (categories aligned to the UN SDGs)

• Sections (types): Research Article · Review Article · Short Communication · Commentary · Editorial
• Categories (subjects): Quality Education · Good Health & Well-being · Clean Water & Sanitation · Affordable & Clean Energy · Climate Action · Sustainable Cities

Here categories act as a thematic index tied to a well-known framework — perfect for a browse block, and a single article can naturally serve more than one goal.

The mistake to avoid: mixing the two lists

The confusion almost always shows up the same way — the same labels appearing in both lists:

❌ Don’t do this

• Sections: Original Research · Pharmacology · Clinical Medicine
• Categories: Original Research · Pharmacology · Clinical Medicine

Here “type” and “subject” are tangled together, so neither list does its job: the Table of Contents is muddled, and topic browsing is meaningless because the topics duplicate the types.

✅ Do this instead

• Sections (types): Original Research Article · Review Article · Case Report · Editorial
• Categories (subjects): Pharmacology · Clinical Medicine · Medicinal Plants · Drug Safety · Hospital Practice

Same content — but now the Table of Contents is clean, and readers can still browse every topic across all issues. Keeping the two lists non-overlapping is exactly the right instinct; it simply works best when **Sections carry the type and Categories carry the *subject***.

Best-practice recommendations

• Keep your section list short and type-based. Six to eight article types is plenty. Long, overlapping section lists make the Table of Contents messy and confuse both authors and indexers.
• Use categories for subjects — and let them overlap freely. Multiple assignment is a feature, not a bug. That’s what makes topic browsing useful.
• Turn on the Browse block (Website Settings → Appearance → Sidebar) so categories are actually visible to readers. Categories with no browse entry point are invisible work.
• Never overload one field with both jobs. If you find yourself creating a section called “Cardiology,” that’s a sign a category is what you actually want.
• State the article type in the PDF, regardless of how your sections are set up. This is what indexes look for.
• Deactivate, don’t delete, when you retire a section that still holds published history.

FAQ

Can an article belong to two sections? No. One section per submission. If you need “an article that’s both a research article and belongs to the cardiology theme,” the theme goes in a category.

Can an article belong to two categories? Yes — as many as make sense.

Do categories affect my DOIs or Crossref deposit? No. DOI/Crossref deposits are article-level and don’t depend on categories. Categories are purely a website browsing feature.

Why does deleting a section feel so hard? Because OJS is protecting your data. A section with even one attached submission can’t be deleted, and forcing it risks orphaning those submissions. Reassign first, then delete.

Still unsure how to structure your journal’s sections and categories — or need help cleaning up an existing setup? OJS-Services.com supports 500+ journals across 29 countries with exactly this kind of configuration and migration work.