Unsupported titles/`lsqb` `rsqb`

[ ] (English name square brackets)

1. Encloses a number of changes in quoted text.
   1. Paraphrase inserted to clarify context.

      [Luke,] I am your father.

   2. Comments about alterations.

      The message said: "Contact them ASAP, their e-mail is [omitted], that's the chance of your life!"

      • 2007 April 6, Atari Online News Etc.‎, volume 9, number 14, page n4:

        Talk about sloooooowww. It’s like 5-minutes odd to boot up on a brand new laptop with so much anti-virus [poop] and gizmo [poop] on it.

   3. Orthographical alterations.

      He said, "[d]on't do it!"

   4. (papyrology, epigraphy) Restored writing that was present in the original text but has since become damaged or broken away.

      Synonym: ‹ ›

   5. (textual criticism, palaeography) Denotes a text deemed interpolated.
   6. See [...] for omissions in quoted text.
2. Encloses a number starting an item in a list.

   Synonym: ( )

   • 1954 February 15, Henry E. Michelson, “The Syndrome of Lupus Erythematosus”, in Modern Medicine, volume 22, number 4, Minneapolis, Minn.: Modern Medicine Publications, Inc., page 96:

     Two distinct types of lupus erythematosus are recognized: [1] chronic or discoid, which is essentially a skin lesion, and [2] severe systemic, designated as acute.

3. (linguistics) Encloses a phonetic transcription.
4. (computing, programming) Encloses optional parameters in syntax help.

   DROP TABLE tbl_name [, tbl_name] ...

• / / (encloses a phonemic representation)
• ⟨ ⟩ (encloses an orthographic representation)
• ⸢ ⸣ (encloses partially broken or missing glyphs)

• [...] (used when omitting a section in quoted text)

[ ]

1. (mathematics) Encloses a mathematical phrase which has increased operator precedence.

   ${\displaystyle 4/(2x+{\textbf {[7+9]}})}$

2. (mathematics) Encloses a polynomial ring.

   ${\displaystyle \mathbb {C} \cong \mathbb {R} \left[x\right]/\left(x^{2}+1\right)}$

3. (mathematics) An alternating bilinear function satisfying the Jacobi identity; typically in the context of and as the operation of a Lie algebra, thus referred to as Lie bracket.

   ${\displaystyle [\cdot ,\cdot ]:V\otimes V\rightarrow V}$

4. (mathematics) Encloses a matrix or vector.

   Synonym: ( )

   ${\displaystyle {\begin{bmatrix}1&9&-13\\20&5&-6\end{bmatrix}}}$

5. (mathematics) Singles out a digit or portion of an equation, for commentary.
   • 1962, Jack Frohlichstein, Mathematical Fun, Games and Puzzles (in English), Courier Corporation, →ISBN, page 47:

     ${\displaystyle {\begin{aligned}72\\{\underline {\ \times 11}}\\7\left[9\right]2\\\end{aligned}}}$

     ${\displaystyle {\text{(7 + 2 = 9 from top factor)}}}$

6. (mathematics) Denotes the least common multiple of two integers.

   [4,6]=12

7. (mathematics) Alternative form of ⌊ ⌋
8. (programming) In a number of programming languages, used as the array index operator, the subscript operator.

   t[1] = "one"

   t[2] = "two"

9. (regular expressions) Matches a single character that is contained within the brackets, including ranges.

   [a-ce] matches "a", "b", "c", or "e"

• (mathematical precedence) ( ), { }

• Bracket on Wikipedia.Wikipedia