Unicode Explained

Headers related to characters

The most important headers that we need for character-related issues have already been

mentioned. They are summarized in Table 10-1 along with some other headers. Not

all of them relate directly to representation characters. In particular, the Subject header

is mentioned here because it should contain the subject of the message in a suitable

natural language, and this raises the question how we can represent non-ASCII data

there.

Table 10-1. Internet message headers related to handling characters

Header name Meaning

Accept-Charset Lists the character encodings accepted (in HTTP).

Accept-Encoding Lists the transfer encodings accepted (in HTTP).

Accept-Language Lists the language preference settings of the user.

Content-Encoding Specifies the transfer encoding of the original data.

Content‑Transfer‑Encoding Specifies the transfer encoding applied.

Content-Language Specifies the language(s) of the content. Rarely used.

Content-Type Specifies the media type and the character encoding.

MIME-Version Indicates the use of MIME, and a specific version.

Subject Specifies the subject (title) of the message.

Transfer-Encoding Specifies the transfer encoding of the message body.

Headers for transfer encoding

As you can see from Table 10-1, there are several headers that may specify a “content

encoding,” which means an additional encoding such as compression. Those headers

differ