The ISO basic Latin alphabet is an international standard (beginning with ISO/IEC 646) for a Latin-script alphabet that consists of two sets (uppercase and lowercase) of 26 letters, codified in various national and international standards and used widely in international communication. They are the same letters that comprise the current English alphabet. Since medieval times, they are also the same letters of the modern Latin alphabet. The order is also important for sorting words into alphabetical order.
The two sets contain the following 26 letters each:
|Uppercase letter set||A||B||C||D||E||F||G||H||I||J||K||L||M||N||O||P||Q||R||S||T||U||V||W||X||Y||Z|
|Lowercase letter set||a||b||c||d||e||f||g||h||i||j||k||l||m||n||o||p||q||r||s||t||u||v||w||x||y||z|
By the 1960s it became apparent to the computer and telecommunications industries in the First World that a non-proprietary method of encoding characters was needed. The International Organization for Standardization (ISO) encapsulated the Latin script in their (ISO/IEC 646) 7-bit character-encoding standard. To achieve widespread acceptance, this encapsulation was based on popular usage. The standard was based on the already published American Standard Code for Information Interchange, better known as ASCII, which included in the character set the 26 × 2 letters of the English alphabet. Later standards issued by the ISO, for example ISO/IEC 8859 (8-bit character encoding) and ISO/IEC 10646 (Unicode Latin), have continued to define the 26 × 2 letters of the English alphabet as the basic Latin script with extensions to handle other letters in other languages.
In ASCII the letters belong to the printable characters and in Unicode since version 1.0 they belong to the block "C0 Controls and Basic Latin". In both cases, as well as in ISO/IEC 646, ISO/IEC 8859 and ISO/IEC 10646 they are occupying the positions in hexadecimal notation 41 to 5A for uppercase and 61 to 7A for lowercase.
The list below only includes alphabets that lack:
Notable omissions due to these rules include Spanish, Esperanto, Filipino and German. The German alphabet is sometimes considered by tradition to contain only 26 letters (with ä, ö, ü considered variants and ß considered a ligature), but the current German orthographic rules include ä, ö, ü, ß in the alphabet placed after Z; however, this order is normally not used in collation: usually ä, ö, ü are collated as a, o, u (or sometimes as ae, oe, ue), ß as ss.
|Alphabet||Diacritic||Multigraphs (not constituting distinct letters)||Ligatures|
|Afrikaans alphabet||á, ä, é, è, ê, ë, í, î, ï, ó, ô, ö, ú, û, ü, ý||Digraphs: ⟨aa⟩, ⟨ai⟩, ⟨ch⟩, ⟨ee⟩, ⟨ei⟩, ⟨eu⟩, ⟨gh⟩, ⟨ie⟩, ⟨nj⟩, ⟨ng⟩ ⟨oe⟩, ⟨oi⟩, ⟨oo⟩, ⟨ou⟩, ⟨sj⟩, ⟨tj⟩, ⟨ts⟩, ⟨ui⟩, ⟨uu⟩
Trigraphs: ⟨aai⟩, ⟨eeu⟩, ⟨oei⟩, ⟨ooi⟩
|Aragonese alphabet (Academia de l'Aragonés orthography)||á, é, í, ó, ú, ü, lꞏl||⟨ch⟩, ⟨gu⟩, ⟨ll⟩, ⟨ny⟩, ⟨qu⟩, ⟨rr⟩, ⟨tz⟩|
|Catalan alphabet||à, é, è, í, ï, ó, ò, ú, ü, ç, lꞏl||⟨gu⟩, ⟨ig⟩, ⟨ix⟩, ⟨ll⟩, ⟨ny⟩, ⟨qu⟩, ⟨rr⟩, ⟨ss⟩|
|Dutch alphabet||ä, é, è, ë, ï, ö, ü||The digraph ⟨ij⟩ is sometimes considered to be a separate letter. When that is the case, it usually replaces or is intermixed with ⟨y⟩. Other digraphs: ⟨aa⟩, ⟨ae⟩, ⟨ai⟩, ⟨au⟩, ⟨ch⟩, ⟨ee⟩, ⟨ei⟩, ⟨eu⟩, ⟨ie⟩, ⟨oe⟩, ⟨oi⟩, ⟨oo⟩, ⟨ou⟩, ⟨ui⟩, ⟨uu⟩|
|English alphabet||only in loanwords (see below)1||⟨sh⟩, ⟨ch⟩, ⟨ea⟩, ⟨ou⟩, ⟨th⟩, ⟨ph⟩, ⟨ng⟩||æ, œ (both archaic)|
|French alphabet||à, â, ç, é, è, ê, ë, î, ï, ô, ù, û, ü, ÿ||⟨ai⟩, ⟨au⟩, ⟨ei⟩, ⟨eu⟩, ⟨oi⟩, ⟨ou⟩, ⟨eau⟩, ⟨ch⟩, ⟨ph⟩, ⟨gn⟩, ⟨an⟩, ⟨am⟩, ⟨en⟩, ⟨em⟩, ⟨in⟩, ⟨im⟩, ⟨on⟩, ⟨om⟩, ⟨un⟩, ⟨um⟩, ⟨yn⟩, ⟨ym⟩, ⟨ain⟩, ⟨aim⟩, ⟨ein⟩, ⟨oin⟩, ⟨aî⟩, ⟨eî⟩||æ (rare), œ (mandatory)|
|Italian alphabet (extended)[a]||à, è, é, ì, ò, ù||⟨ch⟩, ⟨ci⟩, ⟨gh⟩, ⟨gi⟩, ⟨gl⟩, ⟨gli⟩, ⟨gn⟩, ⟨sc⟩, ⟨sci⟩|
|Ido alphabet*||none||⟨qu⟩, ⟨ch⟩, ⟨sh⟩|
|Indonesian alphabet||only in learning materials (see below)3||⟨kh⟩, ⟨ng⟩, ⟨ny⟩, ⟨sy⟩, diphthongs: ⟨ai⟩, ⟨au⟩, ⟨ei⟩, ⟨oi⟩|
|Interlingua alphabet*||only in unassimilated loanwords (see below)2||⟨ch⟩, ⟨ph⟩, ⟨qu⟩, ⟨rh⟩, ⟨sh⟩|
|Javanese Latin alphabet||é, è||⟨dh⟩, ⟨kh⟩, ⟨ng⟩, ⟨ny⟩, ⟨sy⟩, ⟨th⟩|
|Luxembourgish alphabet||ä, é, ë||⟨aa⟩, ⟨ch⟩, ⟨ck⟩, ⟨ee⟩, ⟨ei⟩, ⟨ie⟩, ⟨ii⟩, ⟨ng⟩, ⟨oo⟩, ⟨ou⟩, ⟨qu⟩, ⟨ue⟩, ⟨uu⟩, ⟨sch⟩|
|Malay alphabet||only in learning materials (see below)3||⟨gh⟩, ⟨kh⟩, ⟨ng⟩, ⟨ny⟩, ⟨sy⟩|
|Portuguese alphabet[b]||ã, õ, á, é, í, ó, ú, â, ê, ô, à, ç||⟨ch⟩, ⟨lh⟩, ⟨nh⟩, ⟨rr⟩, ⟨ss⟩, ⟨am⟩, ⟨em⟩, ⟨im⟩, ⟨om⟩, ⟨um⟩, ⟨ãe⟩, ⟨ão⟩, ⟨õe⟩|
|Sundanese Latin alphabet||é||⟨eu⟩, ⟨ng⟩, ⟨ny⟩|
* Constructed languages
The Roman (Latin) alphabet is commonly used for column numbering in a table or chart. This avoids confusion with row numbers using Arabic numerals. For example, a 3-by-3 table would contain Columns A, B, and C, set against Rows 1, 2, and 3. If more columns are needed beyond Z (normally the final letter of the alphabet), the column immediately after Z is AA, followed by AB, and so on (see bijective base-26 system). This can be seen by scrolling far to the right in a spreadsheet program such as Microsoft Excel or LibreOffice Calc.
These are double-digit "letters" for table columns, in the same way that 10 through 99 are double-digit numbers. The Greek alphabet has a similar extended form that uses such double-digit letters if necessary, but it is used for chapters of a fraternity as opposed to columns of a table.
Such double-digit letters for bullet points are AA, BB, CC, etc., as opposed to the number-like place value system explained above for table columns.
The Technical Committee TC1 of ECMA met for the first time in December 1960 to prepare standard codes for Input/Output purposes. On April 30, 1965, Standard ECMA-6 was adopted by the General Assembly of ECMA.