Zero-width non-joiner

ISO keyboard symbol for ZWNJ

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 be printed in their final and initial forms, respectively. This is also an effect of a space character, but a ZWNJ is used when it is desirable to keep the words closer together or to connect a word with its morpheme.

The ZWNJ is encoded in Unicode as U+200C ZERO WIDTH NON-JOINER (HTML ‌ · ‌).

Use of ZWNJ and unit separator for correct typography

In certain languages, the ZWNJ is necessary for unambiguously specifying the correct typographic form of a character sequence.

The ASCII control code unit separator was formerly used.

Correct (with ZWNJ)			Incorrect			Meaning
Display	Picture	Code	Display	Picture	Code
می‌خواهم		می‌خواهم (rendered from right to left): می‌خواهم	میخواهم		میخواهم	Persian 'I want to'
עֲו‌ֹנֹת		עֲו‌ֹנֹת (rendered from right to left): עֲו‌נֹת	עֲוֹנֹת		עֲוֹנֹת	Old Hebrew 'transgressions'
Auf‌lage		Auf‌lage	Auflage		Auflage	German 'edition' (compound of "auf"+"Lage")
Brotzeit		Brot‌zeit			Brotzeit	German (regional) '(kind of) snack' (compound noun "Brot"+"Zeit" = 'bread time'), shown in Fraktur
deaf‌ly		deaf‌ly	deafly		deafly	Not a compound of "dea"+"fly", but the adverb of "deaf"

In the Biblical Hebrew example, the placement of the holam dot to the left of the letter vav ⟨ו⟩ is correct. If a dot were placed over the ⟨ו⟩, it would resemble ⟨עוֹנוֹת⟩, "seasons". In Modern Hebrew, there is no reason to use the ḥolam after the vav, and the ligature is not needed, so it is rarely used in Modern Hebrew typesetting.

In German typography, ligatures may not cross the constituent boundaries within compounds. Thus, in the first German example, the prefix Auf- is separated from the rest of the word to prohibit the ligature fl. Similarly in English, ligatures should not cross morpheme boundaries.^[1][2] For example, in some words 'fly' and 'fish' are morphemes but in others they're not; therefore words like 'deafly' and 'selfish' should not have ligatures (respectively of fl and fi) while 'dayfly' and 'catfish' should have them.

Persian uses this character extensively for certain prefixes, suffixes and compound words,^[3] and is necessary to disambiguate between non-compound words, which uses a full space.

Use of ZWNJ to display alternate forms

In Indic scripts, insertion of a ZWNJ after a consonant either with a halant or before a dependent vowel prevents the characters from being joined properly:

In Devanagari, the characters क् and ष typically combine to form क्ष, but when a ZWNJ is inserted between them, क्‌ष (code: क्‌ष) is seen instead.

In Kannada, the characters ನ್ and ನ combine to from ನ್ನ, but when a ZWNJ is inserted between them, ನ್‌ನ would be seen. That style is typically used to write non-Kannada words in Kannada script:Facebook is written as ಫೇಸ್‌ಬುಕ್ though it can be written as ಫೇಸ್ಬುಕ್. ರಾಜ್‌ಕುಮಾರ್ and ರಾಮ್‌ಗೊಪಾಲ್ are examples of other proper nouns that needs ZWNJ.

Symbol

German T2 keyboard (detail), showing the ZWNJ symbol on the “.” key

The symbol to be used on keyboards which enable the input of the ZWNJ directly is standardized in Amendment 1 (2012) of ISO/IEC 9995-7:2009 "Information technology – Keyboard layouts for text and office systems – Symbols used to represent functions" as symbol number 81, and in IEC 60417 "Graphical Symbols for use on Equipment" as symbol no. IEC 60417-6177-2.

See also

• Zero-width joiner
• Zero-width space
• Word divider

References

1. "When should I not use a ligature in English typesetting?". english.stackexchange.org.
2. Robert Bringhurst (2008). The Elements of Typographic Style. Section 3.3 'Ligatures' (pp 50-53). Hartley & Marks.
3. "The Zero-Width-Non-Joiner". nmelrc.org.

External links

• Using the ZWNJ in Persian