Represents a content-type which we know not to contain text (will never have a charset)
Represents a content-type which we know to contain text, and has a specified charset.
Represents a content-type which we know to contain text, and the charset is known at runtime.
Represents a content-type which we know to contain text, where the charset always has the same predefined value.
Represents a content-type which we know to contain text, and would be better off having a charset, but the client hasn't provided that.
Represents a content-type which we know to contain text, and would be better off having a charset, but the client hasn't provided that. For example, "text/xml" without a charset parameter.