Unsupported titles/Square brackets

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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!"

   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.
   5. See […] for omissions in quoted text.
2. (linguistics) Encloses a phonetic transcription.
3. (computing, programming) Encloses optional parameters in syntax help.

   DROP TABLE tbl_name [, tbl_name] ...

• / / (indicates phonemes)
• ⟨ ⟩ (encloses an orthographic representation)

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

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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) Encloses a matrix or vector.

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

4. (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:

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

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

5. (mathematics) denote the least common multiple of two integers.

   [4,6]=12

6. (mathematics) Alternative form of ⌊ ⌋
7. (programming) In a number of programming languages, encloses each value of an array.

   t[1] = "one"

   t[2] = "two"

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

   [abc] matches "a", "b", or "c"

   [a-z] specifies a range which matches any lowercase letter from "a" to "z"

   [^abc] matches any character other than "a", "b", or "c".

   [^a-z] matches any single character that is not a lowercase letter from "a" to "z"

• (mathematical precedence) ( ), { }

• Bracket on Wikipedia.Wikipedia