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§7.2.1

Bold and Italics

Heavier or slanted type—when is it bold or italic?

✅ NormativeSettled. The requirement holds as written.📄 Page ruleCan be applied from the page alone.Read §7.2.1 in the RFC ↗

The requirement

Bold MUST be written **bold** and italic *italic*, in Markdown, except where the Markdown delimiter cannot close, where <strong> / <em> MUST be used. They MUST be applied only where the printed glyphs are heavier or slanted than their neighbours.

When it applies

HTML elements are reserved for marks Markdown cannot express at all — see Underlined Text (§7.2.12), Superscript and Subscript (§7.2.11) and Highlighted Text (§7.2.5). <b>, <i>, <strong> and <em> MUST NOT be used for ordinary emphasis in the Markdown text.

Reading the examples. Each one pairs a source page with the output the rule expects. ✅ Sample: the rule applies. ❌ Counter-sample: it looks like it applies and does not, or a rendering got it wrong. A non-conforming output, in red, is shown only for contrast. … marks content left out of an excerpt.

The point, in a small example

The source shows the printed appearance; the output shows the precise markup required by this convention. These pages are made up to isolate the rule.

01

✅ SampleConstructedThe rule applies

Preserve bold and italic without inventing emphasis

Only “Urgent” is bold and only “review” is italic. The rest stays plain.

Source page
Bold and Italics — Preserve bold and italic without inventing emphasis. Source page.
Non-conforming output

What the rule rules out.

Markdown
**Urgent review required.**
Expected output
Markdown
**Urgent** *review* required.
Bold and Italics · Source page

Preserve bold and italic without inventing emphasis

Bold and Italics — Preserve bold and italic without inventing emphasis. Source page.

Where ** cannot close

CommonMark cannot close ** or * between a punctuation mark and a letter: **---**To be is not bold when rendered. In exactly that case — the emphasised run ends in punctuation and a letter or digit follows with no space — the run MUST be written with <strong> (bold) or <em> (italic) instead: <strong>---</strong>To be. Everywhere else the Markdown delimiters are used. (Inside HTML table cells, emphasis is always <strong> / <em> — see Bold and Italic Inside Tables (§9.6.2).)

Styling comes from the glyphs, not from the role

The syntax is the easy half. The failure that costs fidelity is styling text because of what it is rather than what it looks like: bolding a heading because headings are usually bold, or bolding a whole column because one cell in it is heavy.

  • Styling MUST be decided from the glyphs on the page, one run of text at a time.
  • A run MUST NOT be styled because of its role (heading, label, total) when its glyphs are not heavier or slanted.
  • Where it cannot be established whether a run is heavier than its neighbours, the run SHOULD be left unstyled. An unmarked run loses a nuance; a wrongly marked one asserts something the page does not print — the never invent failure.

Tables are where this goes wrong most often, and they are judged cell by cell — see Bold and Italic Inside Tables (§9.6.2).

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Rule id text-bold-and-italics · text formatting inline