Should HTML meta charset be lowercase or uppercase?

Question

Normally UTF should be uppercased as it\'s an abbreviation. However, attributes in HTML are normally lowercased.

So, should it be:

Answer 1

As per the W3C:

A case-insensitive match for any character set name for which the IANA [Character Sets] registry has a Name or Alias field labeled as “preferred MIME name”; or, if none of the Alias fields are so labeled, a case-insensitive match for a Name field in the registry.

The specification does not specifically provide for a canonical case. Previously, I would have suggested you just use UTF-8 (from the registry), however the world is moving to lowercase and I now prefer utf-8 as it aligns better with all your other HTML.

Answer 2

The value for charset is case-insensitive.

From w3.org

A case-insensitive match for any character set name for which the IANA [Character Sets] registry has a Name or Alias field labeled as “preferred MIME name”; or, if none of the Alias fields are so labeled, a case-insensitive match for a Name field in the registry.

Link to full document: http://www.w3.org/TR/html-markup/meta.charset.html