Should HTML meta charset be lowercase or uppercase?

html

Solution

The value for charset is case-insensitive.

From spec.whatwg.org

The charset attribute specifies the character encoding used by the document. This is a character encoding declaration. If the attribute is present, its value must be an ASCII case-insensitive match for the string "utf-8".

Link to full document: https://html.spec.whatwg.org/multipage/semantics.html#attr-meta-charset

Problem

Normally `UTF` should be uppercased as it's an abbreviation. However, attributes in HTML are normally lowercased. So, should it be: `<meta charset="UTF-8"/>` or `<meta charset="utf-8"/>`? I know both work. Thank you.

Original source

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