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

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