Bracket
A bracket is either of two tall fore- or back-facing punctuation marks commonly used to isolate a segment of text or data from its surroundings.
[3] They come in four main pairs of shapes, as given in the box to the right, which also gives their names, that vary between British and American English.
Erasmus coined the term lunula to refer to the round brackets or parentheses ( ) recalling the shape of the crescent moon (Latin: luna).
Braces (curly brackets) first became part of a character set with the 8-bit code of the IBM 7030 Stretch.
[citation needed] Parentheses contain adjunctive material that serves to clarify (in the manner of a gloss) or is aside from the main point.
Parentheses may be used in formal writing to add supplementary information, such as "Senator John McCain (R - Arizona) spoke at length".
Again, the parenthesis implies that the meaning and flow of the bracketed phrase is supplemental to the rest of the text and the whole would be unchanged were the parenthesized sentences removed.
An unpaired right parenthesis is often used as part of a label in an ordered list, such as this one: a) educational testing, b) technical writing and diagrams, c) market research, and d) elections.
[31][32] In chemical nomenclature, parentheses are used to distinguish structural features and multipliers for clarity, for example in the polymer poly(methyl methacrylate).
[36] In transcribed interviews, sounds, responses and reactions that are not words but that can be described are set off in square brackets — "... [laughs] ...".
Additionally, a small letter can be replaced by a capital one, when the beginning of the original printed text is being quoted in another piece of text or when the original text has been omitted for succinctness— for example, when referring to a verbose original: "To the extent that policymakers and elite opinion in general have made use of economic analysis at all, they have, as the saying goes, done so the way a drunkard uses a lamppost: for support, not illumination", can be quoted succinctly as: "[P]olicymakers [...] have made use of economic analysis [...] the way a drunkard uses a lamppost: for support, not illumination."
[40] In translated works, brackets are used to signify the same word or phrase in the original language to avoid ambiguity.
Brackets (called move-left symbols or move right symbols) are added to the sides of text in proofreading to indicate changes in indentation: Square brackets are used to denote parts of the text that need to be checked when preparing drafts prior to finalizing a document.
Compare with: (1954) 98 Sol Jo 176This citation reports a decision from 1954, in volume 98 of the Solicitors Journal which may be published in 1955 or later.
They often denote points that have not yet been agreed to in legal drafts and the year in which a report was made for certain case law decisions.
Square brackets can also be used in chemistry to represent the concentration of a chemical substance in solution and to denote charge a Lewis structure of an ion (particularly distributed charge in a complex ion), repeating chemical units (particularly in polymers) and transition state structures, among other uses.
The Quine corners ⌜ and ⌝ have at least two uses in mathematical logic: either as quasi-quotation, a generalization of quotation marks, or to denote the Gödel number of the enclosed expression.
A hole in the papyrus has obliterated βου π, but these letters are supplied by an ancient commentary on the poem.
[55] Braces used to be used to connect multiple lines of poetry, such as triplets in a poem of rhyming couplets,[56] although this usage had gone out of fashion by the 19th century.
[58] Two examples here from Charles Hutton's 19th century table of weights and measures in his A Course of Mathematics: ⎧ ⎪ ⎨ ⎪ ⎩ As an extension to the International Phonetic Alphabet (IPA), braces are used for prosodic notation.
[31] In many programming languages, curly brackets enclose groups of statements and create a local scope.
In many cases, only those characters are accepted by computer programs, and the Unicode angle brackets are not recognized (for instance, in HTML tags).
Unicode discourages their use for mathematics and in Western texts,[15] because they are canonically equivalent to the CJK code points U+300n and thus likely to render as double-width symbols.
[citation needed] In linguistics, angle brackets identify graphemes (e.g., letters of an alphabet) or orthography, as in "The English word /kæt/ is spelled ⟨cat⟩.
Chevron-like symbols are part of standard Chinese, Japanese and – less frequently – Korean punctuation, where they generally enclose the titles of books, as: 〈 ︙ 〉 or 《 ︙ 》 for traditional vertical printing — written in vertical lines — and as 〈 ... 〉 or 《 ... 》 for horizontal printing — in horizontal.
In physical sciences and statistical mechanics, angle brackets are used to denote an average (expected value) over time or over another continuous parameter.
For example: In mathematical physics, especially quantum mechanics, it is common to write the inner product between elements as ⟨a|b⟩, as a short version of ⟨a|·|b⟩, or ⟨a|Ô|b⟩, where Ô is an operator.
They are also used to surround the names of header files; this usage was inherited from and is also found in C. In the Z formal specification language, angle brackets define a sequence.
This use is sometimes extended as an informal mechanism for communicating mood or tone in digital formats such as messaging, for example adding "
Representations of various kinds of brackets in Unicode and their respective HTML entities, that are not in the infoboxes in preceding sections, are given below.
