Research / Constructs / Headings
Markdown headings in five publishing editors
One Markdown fixture, five real publishing editors, tested 2026-08-24. For headings the observed result was a manual step in WordPress; changed in X and LinkedIn; kept in Substack and Beehiiv. Every row below is a rule with its own page and its own dated record.
Matches heading. Fixture markdown-portability-test-v1. Tested 2026-08-24. How these tests are run.
What happens, per destination
| Destination | What happens | Result | Severity | Rule | Confidence | Last tested |
|---|---|---|---|---|---|---|
| WordPress | The post title is not filled by pasting. | Manual step | Action | WP-TITLE-01 | Verified | 2026-08-24 |
| X | Heading markers are removed; the text becomes a standalone line. | Changed | Info | X-HEAD-01 | Verified | 2026-08-24 |
| Heading markers are removed; the first line becomes the opening. | Changed | Review | LI-HEAD-01 | Verified | 2026-08-24 | |
| WordPress | Heading levels are preserved. | Kept | Info | WP-HEAD-01 | Verified | 2026-08-24 |
| Substack | Heading hierarchy survives rich paste. | Kept | Info | SUB-HEAD-01 | Verified | 2026-08-24 |
| Beehiiv | Headings become native headings. | Kept | Info | BEE-HEAD-01 | Verified | 2026-08-24 |
Manual steps this creates
- WordPress: Paste the title into the title field, then decide whether to keep the duplicate H1. (The tested paste left the title field empty and kept the H1 in the body.)
- LinkedIn: Check the opening line works as a hook. (A feed post is not a document. A deep heading hierarchy reads poorly here.)
Limits of what was tested
- Each result describes the surface named beside it, on the date named beside it, and nothing wider.
- A result marked unknown means no dated test covers it. It is not a prediction.
- Rendering is not the same across platform versions, themes, plugins, or email clients.
Prepare a draft
- Check your own draft against all five destinations
- Markdown to WordPress, handoff mode: gutenberg paste
- Markdown to Substack, handoff mode: rich html clipboard
- Markdown to Beehiiv, handoff mode: clean markdown paste
- Markdown to X, handoff mode: plain text
- Markdown to LinkedIn, handoff mode: plain text
Related
- The 6 rules behind this page:
BEE-HEAD-01,LI-HEAD-01,SUB-HEAD-01,WP-HEAD-01,WP-TITLE-01,X-HEAD-01 - Every construct, side by side
- The full five-destination matrix