# Use lowercase after a colon (EK00020)

import { Aside, Badge } from '@astrojs/starlight/components';

Keeping the word after a colon lowercase treats the colon as a continuation rather than a new sentence, so capitalization stays consistent in your documentation. EkLine flags a word that starts with an uppercase letter right after a colon within a sentence (rule EK00020).

## Why use lowercase after a colon in documentation?

A colon introduces a related clause, not a new sentence, so the word after it stays lowercase in most style guides. Mixing uppercase and lowercase after colons across a document looks unedited and distracts readers. A single convention keeps your capitalization predictable.

## What EkLine flags

EK00020 flags a word that starts with an uppercase letter directly after a colon, unless the word is a proper noun.

- ❌ **Incorrect:** Note: This step is required.
- ✅ **Correct:** Note: this step is required.
- ❌ **Incorrect:** Remember: Always back up first.
- ✅ **Correct:** Remember: always back up first.

## How to fix

Lowercase the first letter of the word after the colon. When that word is a proper noun, keep its capitalization and ignore the rule for that line.

<Aside type="note">
A proper noun after a colon, such as "Supported platform: Linux", keeps its capital letter.
</Aside>

## FAQ

### Do you capitalize the first word after a colon?

In most style guides, no. A colon introduces a related clause, not a new sentence, so the following word stays lowercase.

### When does a word after a colon keep its capital letter?

When it is a proper noun. "Supported platform: Linux" keeps the capital because Linux is a name.

## Rule details

| Property | Value |
|----------|-------|
| Rule ID | `EK00020` |
| Category | Sentences and phrases |
| Default severity | <Badge text="Warning" variant="caution" /> |
| Enabled by default | No |

## Ignore this rule

To keep a capitalized word after a colon on one line, add an inline comment with a reason:

```markdown
<!-- ekline-ignore-next-line EK00020 -- capitalized product term -->
Requirement: Enterprise plan users only.
```

To disable the rule across your project, add it to the `ignore` list in your [configuration file](/reviewer/configuration/ignoring-rules/#ignore).

## Related rules

- [EK00023](/reviewer/rules/ek00023/) — Avoid end punctuation in headings
- [EK00037](/reviewer/rules/ek00037/) — Use sentence-style capitalization in headings