empty string
In formal language theory, the empty string, or empty word, is the unique string of length zero.
Formal theory
Formally, a string is a finite, ordered sequence of characters such as letters, digits or spaces. The empty string is the special cas ...
* A
quotation mark
Quotation marks (also known as quotes, quote marks, speech marks, inverted commas, or talking marks) are punctuation marks used in pairs in various writing systems to set off direct speech, a quotation, or a phrase. The pair consists of an ...
(")
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ditto mark
The ditto mark is a shorthand sign, used mostly in hand-written text, indicating that the words or figures above it are to be repeated.
The mark is made using 'a pair of apostrophes'; 'a pair of marks used underneath a word'; the symbol (quota ...
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double acute accent
The double acute accent ( ˝ ) is a diacritic mark of the Latin and Cyrillic scripts. It is used primarily in Hungarian or Chuvash, and consequently it is sometimes referred to by typographers as hungarumlaut. The signs formed with a regular um ...
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double grave accent
The double grave accent ( ̏ ) is a diacritic used in scholarly discussions of the Serbo-Croatian and sometimes Slovene languages. It is also used in the International Phonetic Alphabet.
In Serbo-Croatian and Slovenian, double grave accent is ...
()
* An
umlaut diacritic
The umlaut () is the diacritical mark used to indicate in writing (as part of the letters , , and ) the result of the historical sound shift due to which former back vowels are now pronounced as front vowels (for example , , and as , , and ) ...
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diaeresis diacritic
The diaeresis ( ; is a diacritical mark used to indicate the separation of two distinct vowels in adjacent syllables when an instance of Hiatus (linguistics), diaeresis (or hiatus) occurs, so as to distinguish from a digraph (orthography), digra ...