The combining grapheme joiner (CGJ), is a
Unicode
Unicode, formally The Unicode Standard,The formal version reference is is an information technology standard for the consistent encoding, representation, and handling of text expressed in most of the world's writing systems. The standard, ...
character that has no visible glyph and is "default ignorable" by applications. Its name is a
misnomer
A misnomer is a name that is incorrectly or unsuitably applied. Misnomers often arise because something was named long before its correct nature was known, or because an earlier form of something has been replaced by a later form to which the name ...
and does not describe its function: the character does not join graphemes.
Its purpose is to semantically ''separate'' characters that should ''not'' be considered
digraphs as well as to block canonical reordering of
combining marks during
normalization.
For example, in a
Hungarian language
Hungarian () is an Uralic language spoken in Hungary and parts of several neighbouring countries. It is the official language of Hungary and one of the 24 official languages of the European Union. Outside Hungary, it is also spoken by Hungar ...
context, adjoining letters ''c'' and ''s'' would normally be considered equivalent to the
cs digraph. If they are separated by the CGJ, they will be considered as two separate graphemes. However, in contrast to the
zero-width joiner and similar characters, the CGJ does not affect whether the two letters are ''rendered'' separately or as a
ligature or cursively joined—the default behavior for this is determined by the font.
The CGJ is also needed for
complex scripts
Complex text layout (CTL) or complex text rendering is the typesetting of writing systems in which the shape or positioning of a grapheme depends on its relation to other graphemes. The term is used in the field of software internationalizati ...
. For example, in most cases the
Hebrew cantillation
Hebrew cantillation is the manner of chanting ritual readings from the Hebrew Bible in synagogue services. The chants are written and notated in accordance with the special signs or marks printed in the Masoretic Text of the Bible, to comple ...
accent
metheg
Meteg (or meseg or metheg, Hebrew: , lit. 'bridle', also , lit. 'bellowing', , or ) is a punctuation mark used in Biblical Hebrew for stress marking. It is a vertical bar placed under the affected syllable.
Usage
Meteg is primarily used i ...
is supposed to appear to the left of the
vowel point and by default most display systems will render it like this even if it is typed before the vowel. But in some words in
Biblical Hebrew
Biblical Hebrew (, or , ), also called Classical Hebrew, is an archaic form of the Hebrew language, a language in the Canaanite branch of Semitic languages spoken by the Israelites in the area known as the Land of Israel, roughly west of t ...
the metheg appears to the right of the vowel, and to tell the display engine to render it properly on the right, CGJ must be typed between the metheg and the vowel. Compare:
In the case of several consecutive
combining diacritics
In digital typography, combining characters are characters that are intended to modify other characters. The most common combining characters in the Latin script are the combining diacritical marks (including combining accents).
Unicode also ...
, an intervening CGJ indicates that they should not be subject to canonical reordering.
In contrast, the "
zero-width non-joiner
The zero-width non-joiner (ZWNJ) is a non-printing character used in the computerization of writing systems that make use of ligatures. When placed between two characters that would otherwise be connected into a ligature, a ZWNJ causes them to b ...
" at U+200C in the
General Punctuation range, which prevents two adjacent character from turning into a ligature.
References
External links
Unicode FAQ - Characters and Combining Marks
{{Unicode navigation
Unicode special code points
Control characters