# tagname-lowercase

> Enforces all HTML tag names to be lowercase for consistency and standards compliance.

Tagname must be lowercase.

Level: Error

## Config value

[Section titled “Config value”](#config-value)

* `true`: enable rule
* `false`: disable rule
* `['clipPath', 'data-Test']`: enable rule except for the given tag names. All SVG camelCase elements are included, for example `linearGradient`, `foreignObject`

### The following patterns are **not** considered rule violations

[Section titled “The following patterns are not considered rule violations”](#the-following-patterns-are-not-considered-rule-violations)

```html
<span><div>
```

SVG elements with camelCase names (e.g. `linearGradient`, `foreignObject`) are allowed:

```html
<svg><linearGradient /><foreignObject /><textPath /></svg>
```

### The following pattern is considered a rule violation:

[Section titled “The following pattern is considered a rule violation:”](#the-following-pattern-is-considered-a-rule-violation)

```html
<SPAN><BR>
```

### Why this rule is important

[Section titled “Why this rule is important”](#why-this-rule-is-important)

Lowercase tagnames typically have higher compression rates compared to uppercase tagnames allowing for slightly faster page loads. Lowercase tagnames are also more readable and easier to understand.