MR
Mayur Rathi
@github
⭐ 34.1k GitHub stars

Em-Dash

Em-Dash is an writing AI skill with a core value of Expert on the history, origin, and correct use of the em dash. It helps developers solve real-world problems in the writing domain, boosting efficiency, automating repetitive tasks, and optimizing workflows.

Expert on the history, origin, and correct use of the em dash. Use when writing or reviewing code, comments, or data files to avoid em and en dashes, defaulting to never using them and replacing any f

Last verified on: 2026-06-28
mkdir -p ./skills/em-dash && curl -sfL https://raw.githubusercontent.com/github/awesome-copilot/main/skills/em-dash/SKILL.md -o ./skills/em-dash/SKILL.md

Run in terminal / PowerShell. Requires curl (Unix) or PowerShell 5+ (Windows).

Skill Content

# em dash


The **em dash** (U+2014, `\u2014`; not the hyphen-minus `-`) is the longest

of the standard dashes, and is the Swiss Army knife of punctuation. Its history

is a fascinating journey from handwritten manuscripts to mechanical

constraints, literary rebellion, and modern digital dominance.


Here is a breakdown of how the em dash evolved:


History of the em dash


Early Beginnings (15th-18th Century)


- The First Dashes: Early appearances of the dash in English literature date

back to 1580 in private letters and 1588 in English drama. They were often

used to indicate pauses, self-interruption, or an unfinished thought

- Gutenberg and Early Printing: The em dash officially emerged as a standardized

typesetting mark during the 15th-century printing revolution


#### The Etymology


- The "M" Width: The em dash is named because its standard length is equal to

the width of the capital letter "M" in the specific typeface being used

(Similarly, the slightly shorter en dash is the width of the letter "N")


Literary Popularity (17th-19th Century)


- The Author's Tool: By the 17th and 18th centuries, it became a beloved tool

for writers mimicking the natural lurches, stutters, and rhythms of speech

- Dickinson Dashes: In the 19th century, poets like Emily Dickinson famously

used the em dash for emotional weight, rhythm, and to invite reader

interpretation. This became so synonymous with her work that they are often

informally called "Dickinson Dashes"


The Typewriter Era (19th-20th Century)


- The Double-Hyphen Compromise: When typewriters were introduced, they lacked

a dedicated key for the em dash. To compensate, typists began using two

consecutive hyphens (--)

- The No-Space Rule: Because of this mechanical compromise, a stylistic

convention of typing the mark without surrounding spaces emerged and remains


The Digital Age (Present Day)


- Return to Form: Modern digital typesetting and word processing programs have

restored the true, unbroken em dash

- **Modern Renaissance**: The em dash is experiencing a resurgence of popularity

- It has become a hallmark of modern long-form prose and is also a favorite,

heavily used punctuation mark in AI outputs, which often prioritize a

conversational, stream-of-consciousness style


#### Speculation for em Dash Modern Renaissance


- Professional authors who had to meet deadlines and did not have the time to

strictly proofread the online article before submitting it

- Professionals who wanted to show off their knowledge of HTML encoding in order

to seem smart

- Graphic designers who wanted to make the visual composition of text on a web

page more appealing

- The fact that popularity begets popularity

- People publishing web articles saw that everyone else was using em dashes,

so instead of using a hyphen where one belonged, they opted to use an em dash


Analysis of em dash History


Nowhere in the history of the em dash was it intentionally used in the writing

of computer code, or files meant to be executed as computer instructions.


When to use em or en dashes


Never.


In Code Files


> [!IMPORTANT]

> Never.

> In no way, shape, form, or fashion is tone ever important in code comments.


- **Never**

- Use the `-` (hyphen) character instead

- If working as an agent, and an em dash is in a comment, then replace it

with the `-` (hyphen) character


In Raw Data and/or Text Files


> [!NOTE]

> Default to **never**


- When instructed to, and it is 100% clear that the text is to be used as:

- Literature

- News

- If working as an agent, and an em dash is already part of the data, then

leave it


Other Punctuation Characters


As part of being an em dash expert comes the knowledge of other punctuation marks

or characters.


End-of-Sentence Marks


Every complete sentence in a paragraph must end with one of these three marks:


- Period `.`: Ends statements and declarative sentences

- Keyboard character: `true`

- Programming langu

🎯 Best For

  • Engineering teams doing code reviews
  • Open source maintainers
  • GitHub Copilot users
  • Claude users
  • Content creators

💡 Use Cases

  • Reviewing pull requests for security vulnerabilities
  • Checking code style consistency
  • Content creation
  • Style guide enforcement

📖 How to Use This Skill

  1. 1

    Install the Skill

    Copy the install command from the Terminal tab and run it. The SKILL.md file downloads to your local skills directory.

  2. 2

    Load into Your AI Assistant

    Open GitHub Copilot or Claude and reference the skill. Paste the SKILL.md content or use the system prompt tab.

  3. 3

    Apply Em-Dash to Your Work

    Provide context for your task — paste source material, describe your audience, or share existing work to guide the AI.

  4. 4

    Review and Refine

    Edit the AI output for accuracy, tone, and completeness. Add human insight where the AI lacks context.

❓ Frequently Asked Questions

Does this skill check for OWASP Top 10?

Security-focused review skills often include OWASP checks. Check the skill content for specific vulnerability categories covered.

Can Em-Dash maintain my brand voice?

Yes — provide style guides or example content in your prompt for consistent brand-aligned output.

How do I install Em-Dash?

Copy the install command from the Terminal tab and run it. The skill downloads to ./skills/em-dash/SKILL.md, ready to use.

Can I customize this skill for my team?

Absolutely. Edit the SKILL.md file to add team-specific instructions, examples, or workflows.

⚠️ Common Mistakes to Avoid

Blindly accepting AI suggestions

Always verify AI-generated review comments. Some suggestions may not apply to your specific codebase conventions.

Publishing unedited drafts

AI writing needs human editing for facts, flow, and authentic voice.

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