• Alias: l||. • Matchfix operator. • x is by default interpreted as DoubleBracketingBar[x]. • Used in mathematics to indicate taking a norm. • Sometimes used for determinant. • Sometimes used to indicate a matrix. • Not the same as \[DoubleVerticalBar]. • Drawn in monospaced fonts with a small left -pointing tee to indicate direction. • Extensible character. • See also: \[LeftBracketingBar] .
\[LeftDoubleBracketingBar]
l||
x 
is by default interpreted as DoubleBracketingBar[x]. 