MD025 - Multiple top level headers in the same document

Tags: headers

Aliases: single-h1

Parameters: level (number; default 1)

This rule is triggered when a top level header is in use (the first line of the file is a h1 header), and more than one h1 header is in use in the document:

# Top level header

# Another top level header

To fix, structure your document so that there is a single h1 header that is the title for the document, and all later headers are h2 or lower level headers:

# Title

## Header

## Another header

Rationale: A top level header is a h1 on the first line of the file, and serves as the title for the document. If this convention is in use, then there can not be more than one title for the document, and the entire document should be contained within this header.

Note: The level parameter can be used to change the top level (ex: to h2) in cases where an h1 is added externally.

MD001 - Header levels should only increment by one level at a time

Tags: headers

Aliases: header-increment

This rule is triggered when you skip header levels in a markdown document, for example:

# Header 1

### Header 3

We skipped out a 2nd level header in this document

When using multiple header levels, nested headers should increase by only one level at a time:

# Header 1

## Header 2

### Header 3

#### Header 4

## Another Header 2

### Another Header 3

MD025 - Multiple top level headers in the same document

Tags: headers

Aliases: single-h1

Parameters: level (number; default 1)

This rule is triggered when a top level header is in use (the first line of the file is a h1 header), and more than one h1 header is in use in the document:

# Top level header

# Another top level header

To fix, structure your document so that there is a single h1 header that is the title for the document, and all later headers are h2 or lower level headers:

# Title

## Header

## Another header

Rationale: A top level header is a h1 on the first line of the file, and serves as the title for the document. If this convention is in use, then there can not be more than one title for the document, and the entire document should be contained within this header.

Note: The level parameter can be used to change the top level (ex: to h2) in cases where an h1 is added externally.

MD001 - Header levels should only increment by one level at a time

Tags: headers

Aliases: header-increment

This rule is triggered when you skip header levels in a markdown document, for example:

# Header 1

### Header 3

We skipped out a 2nd level header in this document

When using multiple header levels, nested headers should increase by only one level at a time:

# Header 1

## Header 2

### Header 3

#### Header 4

## Another Header 2

### Another Header 3

MD025 - Multiple top level headers in the same document

Tags: headers

Aliases: single-h1

Parameters: level (number; default 1)

This rule is triggered when a top level header is in use (the first line of the file is a h1 header), and more than one h1 header is in use in the document:

# Top level header

# Another top level header

To fix, structure your document so that there is a single h1 header that is the title for the document, and all later headers are h2 or lower level headers:

# Title

## Header

## Another header

Rationale: A top level header is a h1 on the first line of the file, and serves as the title for the document. If this convention is in use, then there can not be more than one title for the document, and the entire document should be contained within this header.

Note: The level parameter can be used to change the top level (ex: to h2) in cases where an h1 is added externally.

MD013 - Line length

Tags: line_length

Aliases: line-length

Parameters: linelength, ignorecodeblocks, codeblocks, tables (number; default 80, boolean; default false, boolean; default true, boolean; default true)

This rule is triggered when there are lines that are longer than the configured line length (default: 80 characters). To fix this, split the line up into multiple lines.

This rule has an exception where there is no whitespace beyond the configured line length. This allows you to still include items such as long URLs without being forced to break them in the middle.

You also have the option to exclude this rule for code blocks. To do this, set the ignore_code_blocks parameter to true. To exclude this rule for tables set the tables parameters to false. Setting the parameter code_blocks to false to exclude the rule for code blocks is deprecated and will be removed in a future release.

Code blocks are included in this rule by default since it is often a requirement for document readability, and tentatively compatible with code rules. Still, some languages do not lend themselves to short lines.

MD025 - Multiple top level headers in the same document

Tags: headers

Aliases: single-h1

Parameters: level (number; default 1)

This rule is triggered when a top level header is in use (the first line of the file is a h1 header), and more than one h1 header is in use in the document:

# Top level header

# Another top level header

To fix, structure your document so that there is a single h1 header that is the title for the document, and all later headers are h2 or lower level headers:

# Title

## Header

## Another header

Rationale: A top level header is a h1 on the first line of the file, and serves as the title for the document. If this convention is in use, then there can not be more than one title for the document, and the entire document should be contained within this header.

Note: The level parameter can be used to change the top level (ex: to h2) in cases where an h1 is added externally.

MD024 - Multiple headers with the same content

Tags: headers

Aliases: no-duplicate-header

Parameters: allowdifferentnesting (boolean; default false)

This rule is triggered if there are multiple headers in the document that have the same text:

# Some text

## Some text

To fix this, ensure that the content of each header is different:

# Some text

## Some more text

Rationale: Some markdown parses generate anchors for headers based on the header name, and having headers with the same content can cause problems with this.

If the parameter allow_different_nesting is set to true, header duplication under different nesting is allowed, like it usually happens in change logs:

# Change log

## 2.0.0

### Bug fixes

### Features

## 1.0.0

### Bug fixes

MD013 - Line length

Tags: line_length

Aliases: line-length

Parameters: linelength, ignorecodeblocks, codeblocks, tables (number; default 80, boolean; default false, boolean; default true, boolean; default true)

This rule is triggered when there are lines that are longer than the configured line length (default: 80 characters). To fix this, split the line up into multiple lines.

This rule has an exception where there is no whitespace beyond the configured line length. This allows you to still include items such as long URLs without being forced to break them in the middle.

You also have the option to exclude this rule for code blocks. To do this, set the ignore_code_blocks parameter to true. To exclude this rule for tables set the tables parameters to false. Setting the parameter code_blocks to false to exclude the rule for code blocks is deprecated and will be removed in a future release.

Code blocks are included in this rule by default since it is often a requirement for document readability, and tentatively compatible with code rules. Still, some languages do not lend themselves to short lines.

MD024 - Multiple headers with the same content

Tags: headers

Aliases: no-duplicate-header

Parameters: allowdifferentnesting (boolean; default false)

This rule is triggered if there are multiple headers in the document that have the same text:

# Some text

## Some text

To fix this, ensure that the content of each header is different:

# Some text

## Some more text

Rationale: Some markdown parses generate anchors for headers based on the header name, and having headers with the same content can cause problems with this.

If the parameter allow_different_nesting is set to true, header duplication under different nesting is allowed, like it usually happens in change logs:

# Change log

## 2.0.0

### Bug fixes

### Features

## 1.0.0

### Bug fixes

MD025 - Multiple top level headers in the same document

Tags: headers

Aliases: single-h1

Parameters: level (number; default 1)

This rule is triggered when a top level header is in use (the first line of the file is a h1 header), and more than one h1 header is in use in the document:

# Top level header

# Another top level header

To fix, structure your document so that there is a single h1 header that is the title for the document, and all later headers are h2 or lower level headers:

# Title

## Header

## Another header

Rationale: A top level header is a h1 on the first line of the file, and serves as the title for the document. If this convention is in use, then there can not be more than one title for the document, and the entire document should be contained within this header.

Note: The level parameter can be used to change the top level (ex: to h2) in cases where an h1 is added externally.

MD001 - Header levels should only increment by one level at a time

Tags: headers

Aliases: header-increment

This rule is triggered when you skip header levels in a markdown document, for example:

# Header 1

### Header 3

We skipped out a 2nd level header in this document

When using multiple header levels, nested headers should increase by only one level at a time:

# Header 1

## Header 2

### Header 3

#### Header 4

## Another Header 2

### Another Header 3

MD025 - Multiple top level headers in the same document

Tags: headers

Aliases: single-h1

Parameters: level (number; default 1)

This rule is triggered when a top level header is in use (the first line of the file is a h1 header), and more than one h1 header is in use in the document:

# Top level header

# Another top level header

To fix, structure your document so that there is a single h1 header that is the title for the document, and all later headers are h2 or lower level headers:

# Title

## Header

## Another header

Rationale: A top level header is a h1 on the first line of the file, and serves as the title for the document. If this convention is in use, then there can not be more than one title for the document, and the entire document should be contained within this header.

Note: The level parameter can be used to change the top level (ex: to h2) in cases where an h1 is added externally.

MD001 - Header levels should only increment by one level at a time

Tags: headers

Aliases: header-increment

This rule is triggered when you skip header levels in a markdown document, for example:

# Header 1

### Header 3

We skipped out a 2nd level header in this document

When using multiple header levels, nested headers should increase by only one level at a time:

# Header 1

## Header 2

### Header 3

#### Header 4

## Another Header 2

### Another Header 3

MD025 - Multiple top level headers in the same document

Tags: headers

Aliases: single-h1

Parameters: level (number; default 1)

This rule is triggered when a top level header is in use (the first line of the file is a h1 header), and more than one h1 header is in use in the document:

# Top level header

# Another top level header

To fix, structure your document so that there is a single h1 header that is the title for the document, and all later headers are h2 or lower level headers:

# Title

## Header

## Another header

Rationale: A top level header is a h1 on the first line of the file, and serves as the title for the document. If this convention is in use, then there can not be more than one title for the document, and the entire document should be contained within this header.

Note: The level parameter can be used to change the top level (ex: to h2) in cases where an h1 is added externally.

MD001 - Header levels should only increment by one level at a time

Tags: headers

Aliases: header-increment

This rule is triggered when you skip header levels in a markdown document, for example:

# Header 1

### Header 3

We skipped out a 2nd level header in this document

When using multiple header levels, nested headers should increase by only one level at a time:

# Header 1

## Header 2

### Header 3

#### Header 4

## Another Header 2

### Another Header 3

MD025 - Multiple top level headers in the same document

Tags: headers

Aliases: single-h1

Parameters: level (number; default 1)

This rule is triggered when a top level header is in use (the first line of the file is a h1 header), and more than one h1 header is in use in the document:

# Top level header

# Another top level header

To fix, structure your document so that there is a single h1 header that is the title for the document, and all later headers are h2 or lower level headers:

# Title

## Header

## Another header

Rationale: A top level header is a h1 on the first line of the file, and serves as the title for the document. If this convention is in use, then there can not be more than one title for the document, and the entire document should be contained within this header.

Note: The level parameter can be used to change the top level (ex: to h2) in cases where an h1 is added externally.

MD025 - Multiple top level headers in the same document

Tags: headers

Aliases: single-h1

Parameters: level (number; default 1)

This rule is triggered when a top level header is in use (the first line of the file is a h1 header), and more than one h1 header is in use in the document:

# Top level header

# Another top level header

To fix, structure your document so that there is a single h1 header that is the title for the document, and all later headers are h2 or lower level headers:

# Title

## Header

## Another header

Rationale: A top level header is a h1 on the first line of the file, and serves as the title for the document. If this convention is in use, then there can not be more than one title for the document, and the entire document should be contained within this header.

Note: The level parameter can be used to change the top level (ex: to h2) in cases where an h1 is added externally.

MD001 - Header levels should only increment by one level at a time

Tags: headers

Aliases: header-increment

This rule is triggered when you skip header levels in a markdown document, for example:

# Header 1

### Header 3

We skipped out a 2nd level header in this document

When using multiple header levels, nested headers should increase by only one level at a time:

# Header 1

## Header 2

### Header 3

#### Header 4

## Another Header 2

### Another Header 3

MD001 - Header levels should only increment by one level at a time

Tags: headers

Aliases: header-increment

This rule is triggered when you skip header levels in a markdown document, for example:

# Header 1

### Header 3

We skipped out a 2nd level header in this document

When using multiple header levels, nested headers should increase by only one level at a time:

# Header 1

## Header 2

### Header 3

#### Header 4

## Another Header 2

### Another Header 3