ISO Latin 9 as compared with ISO Latin 1

The ISO Latin 9 (ISO 8859-15) character set differs from the well-known ISO Latin 1 (ISO 8859-1) character set in a few positions only. The euro sign and some national letters used e.g. in French and Finnish have been introduced and some rarely used special characters omitted.

ISO Latin 9 is a relatively new addition to the ISO 8859 family of character sets, published as a standard 1999-03-15 by ISO. The final proof is available on the Web in PDF format both as English version and as French version.

ISO Latin 9 differs from the widely used ISO Latin 1 (ISO 8859-1) in some character positions only. When viewed as a modification of ISO Latin 1, ISO Latin 9 replaces some rarely needed characters by euro sign - a politically important symbol for the currency of the European Monetary Union (EMU) - and the letters oe ligature and capital Y with diaeresis (used in French) and letters s with caron and z with caron (used in Finnish and other languages). The following table presents the differences in detail.

Code position ISO Latin 1 ISO Latin 9
dec oct hex glyph U+nnnn Unicode name glyph U+nnnn Unicode name
164 244 A4 ¤ U+00A4 currency symbol [euro] U+20AC euro sign
166 246 A6 ¦ U+00A6 broken bar [S caron] U+0160 latin capital letter s with caron
168 250 A8 ¨ U+00A8 diaeresis [s caron] U+0161 latin small letter s with caron
180 264 B4 ´ U+00B4 acute accent [Z caron] U+017D latin capital letter z with caron
184 270 B8 ¸ U+00B8 cedilla [z caron] U+017E latin small letter z with caron
188 274 BC ¼ U+00BC vulgar fraction one quarter [OE] U+0152 latin capital ligature oe
189 275 BD ½ U+00BD vulgar fraction one half [oe] U+0153 latin small ligature oe
190 276 BE ¾ U+00BE vulgar fraction three quarters [Y¨] U+0178 latin capital letter y with diaeresis

General notes

Originally the project which lead to the creation of ISO Latin 9 used the working name "Latin Alphabet Number Zero" for it. Therefore it has often been referred to as "Latin 0".

The famous ISO 8859 Alphabet Soup document contains a complete ISO Latin 9 code table.

Within the European Union (EU), the euro currency has great political and practical importance. The euro sign is both a character that will be used widely and a symbol of the monetary union. Therefore, within EU, and in countries applying for EU membership, it is a crucial requirement that euro sign is available. For technical information on this, see section Euro symbol in IT impact of the Euro (archived site).

ISO Latin 9 contains both euro sign and some important national letters, and the ISO Latin 1 characters replaced by them are very rarely used, as the document The ISO Latin 1 character repertoire - a description with usage notes explains in some detail. Since eight-bit character encodings are still very important, it seems more than likely that ISO Latin 1 will be generally replaced by ISO Latin 9, within Europe at least.

Some of the ISO Latin 9 characters which do not belong to ISO Latin 1 appear in the so-called Windows character set (WinLatin1) as originally defined. These characters are s with caron, oe ligature, and capital Y with diaeresis. Moreover, the euro sign has been added (using code position 80 hexadecimal) into new variants of the Windows character sets. This means that glyphs for the characters are widely available on PCs, although an update may be needed for the euro sign, but the use of the characters requires solutions to character encoding problems. Compare with the document On the use of some MS Windows characters in HTML, which explains the problems caused by differences between ISO Latin 1 and the MS Windows character set. Using ISO Latin 9, some of these problems can be solved.

However, changing from ISO Latin 1 to ISO Latin 9 is a complicated task, partly because so many program assume ISO Latin 1 as the default character set. See section Information about encoding in A tutorial on character code issues for the big picture. In particular, a program which sends ISO Latin 9 encoded text data over the Internet, e.g. by E-mail or using the HTTP protocol, should specify
Content-Type: text/plain;charset=iso-8859-15.

There are detailed instructions on making some E-mail programs (Outlook Express, Pine, Mutt) ISO Latin 9 capable, as well as about using it on terminals, in the document set How to use Latin 9 aka iso-8859-15 in email by Janne K. Edelmann.

Notes on the characters

The euro sign, denoting the currency of the European Monetary Union (EMU), was added to Unicode, in version 2.1 as U+20AC. Notice that it is distinct from the euro-currency sign (U+20A0), which is of minor historical interest only. The presentation of the euro sign is problematic especially in contexts where data needs to be transmitted over networks or otherwise from one data processing system to another, e.g. on Web pages, on Usenet, and E-mail. Generally, in such situations it is still preferable to use the word "euro", in applicable language, orthography, and form; cf. to The euro sign in HTML. See Spelling of the words "euro" and "cent" in the official Community languages (also available in PDF format, where the Greek words are presented properly). In special situations, like international banking business, where ISO 4217 codes are used for currencies, the abbreviation to be used is EUR.

Letters "s" and "z" with caron are used in the official orthography of the Finnish language; see an official statement on this (available in Finnish, too) . (In practice, they are quite often replaced by character pairs "sh" and "zh", partly due to character code and font problems.) They are also used e.g. in Estonian and Czech as well as in the official international transliteration (Latinization, Romanization) scheme for the Cyrillic alphabet, ISO 9. Note that even the part of ISO 9 which is needed for Russian contains, especially in its current version, other characters with diacritics which are outside ISO Latin 9.

The ligature of "o" and "e" is considered as a separate character in French. It is also used e.g. in one style of writing Latin (cf. to the use of "the letter ae" as a ligature of "a" and "e", e.g. writing "Caesar" as "Cæsar").

The latin capital letter y with diaeresis is used in some French names when they are written in capital letters.