HTTP: The Definitive Guide

Character Sets and HTTP

So, let’s jump right into the most important (and confusing) aspects of web internationalization—international alphabetic scripts and their character set encodings.

Web character set standards can be pretty confusing. Lots of people get frustrated when they first try to write international web software, because of complex and inconsistent terminology, standards documents that you have to pay to read, and unfamiliarity with foreign languages. This section and the next section should make it easier for you to use character sets with HTTP.

Charset Is a Character-to-Bits Encoding

The HTTP charset values tell you how to convert from entity content bits into characters in a particular alphabet. Each charset tag names an algorithm to translate bits to characters (and vice versa). The charset tags are standardized in the MIME character set registry, maintained by the IANA (see http://www.iana.org/assignments/character-sets). Appendix H summarizes many of them.

The following Content-Type header tells the receiver that the content is an HTML file, and the charset parameter tells the receiver to use the iso-8859-6 Arabic character set decoding scheme to decode the content bits into characters:

Content-Type: text/html; charset=iso-8859-6

The iso-8859-6 encoding scheme maps 8-bit values into both the Latin and Arabic alphabets, including numerals, punctuation and other symbols.^[1] For example, in Figure 16-1, the highlighted bit pattern has code value 225, which (under ...