The GL area contains the G0 set of ISO/IEC 4873, namely ISO-IR 6, the ASCII character set. The GR area contains characters in 86 of the 96 available code positions, the remaining 10 positions being excluded from use. The 13 characters in column 12, there being three unassigned positions in this column, are non-spacing diacritical marks (combining characters). The characters in all other columns are spacing (non-combining) characters.
Due to its use of non-spacing diacritical marks, the code can represent more characters than there are code positions. The standard includes a normative specification of the 333 graphic characters, including the SPACE character, that it is permitted to represent by use of the 181 bit combinations that are assigned in the code. This set of 333 graphic characters constitutes the repertoire of the standard.
ISO/IEC 6937 specifies a character set that is primarily intended for information interchange using the Latin script. Characters with diacritical marks (accents) are transmitted by sending a non-spacing accent character (the combining character) followed by the underlying letter character. The available diacritical marks are:
The approach adopted by this standard originates with electromechanical devices such as teleprinters. In such devices it is not difficult to prevent certain characters from operating the escapement mechanism that moves to the next printing position. It is an approach that is unsuitable for most data and text processing applications. It does have advantages, however, for sorting (collating) purposes since the underlying letter is easily identified.
The repertoire is suitable for use with a wide range of languages. In particular it contains all the characters of all of the codes known as Latin Alphabets Nos. 1 to 6 that are defined in parts of ISO/IEC 8859, and some additional characters as well. However, it does not contain some of the characters of the codes known as Latin Alphabets Nos. 7 to 9 that are defined in other parts of ISO/IEC 8859. There are no plans to add these missing characters, in particular, the EURO SIGN. It states that it covers the following languages:
However, it also provides an informative note that it does not cover the full repertoire required for Welsh. The missing characters are W and w with acute and grave accents and with diaeresis, and Y and y with grave accents. These characters are all included in ISO-IR 182, which may be used with ISO-IR 6 to form a Welsh variant of Latin Alphabet No.1. They are also included in the newer Latin Alphabet No. 8 defined in ISO/IEC 8859-14 together with missing characters needed for other Celtic languages. See the guide to ISO/IEC 8859 for more details.
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