The default character set for an HTTP message, if none is specified in the Content-Type header. From the HTTP 1.1 specification
section 3.7.1 (http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.7.1):
The "charset" parameter is used with some media types to define the character set (section 3.4) of the data.
When no explicit charset parameter is provided by the sender, media subtypes of the "text" type are defined to
have a default charset value of "ISO-8859-1" when received via HTTP. Data in character sets other than
"ISO-8859-1" or its subsets MUST be labeled with an appropriate charset value.