Markdown Preflight

Research / Rules / SUB-HEAD-01

SUB-HEAD-01

Heading hierarchy survives rich paste. This applies to Substack, where the result is kept.

Affects Substack. Matches heading. Fixture markdown-portability-test-v1.

What happens, per destination

Every destination that applies SUB-HEAD-01, with the live test behind it.
DestinationTested surfaceResultSeverityConfidenceLast tested
SubstackSubstack web post editorKeptInfoVerifiedTested 2026-08-24.

Why, and what to do

H1 through H6 survived the tested rich paste. The publication title stays a separate decision.

No manual step is needed for this rule.

Limits of this rule

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