ISO/IEC 8859 - Introduction

Introduction

While the bit patterns of the 95 printable ASCII characters are sufficient to exchange information in modern English, most other languages that use Latin-derived alphabets need additional symbols not covered by ASCII, such as ß (German), ñ (Spanish), å (Swedish and other Nordic languages) and ő (Hungarian). ISO/IEC 8859 sought to remedy this problem by utilizing the eighth bit in an 8-bit byte to allow positions for another 96 printable characters. Early encodings were limited to 7 bits because of restrictions of some data transmission protocols, and partially for historical reasons. However, more characters were needed than could fit in a single 8-bit character encoding, so several mappings were developed, including at least ten suitable for various Latin-derived alphabets.

The ISO/IEC 8859-n encodings only contain printable characters, and were designed to be used in conjunction with control characters mapped to the unassigned bytes. To this end a series of encodings registered with the IANA add the C0 control set (control characters mapped to bytes 0 to 31) from ISO 646 and the C1 control set (control characters mapped to bytes 128 to 159) from ISO 6429, resulting in full 8-bit character maps with most, if not all, bytes assigned. These sets have ISO-8859-n as their preferred MIME name or, in cases where a preferred MIME name isn't specified, their canonical name. Many people use the terms ISO/IEC 8859-n and ISO-8859-n interchangeably. ISO/IEC 8859-11 did not get such a charset assigned, presumably because it was almost identical to TIS 620.