ChessboardDistance[u, v] gives the chessboard, Chebyshev, or sup norm distance between vectors u and v.
DefaultElement is an option for Grid and related constructs which specifies what to insert when a new element is interactively created.
DefaultFontProperties is a global option that specifies various properties of a font family, such as its character encoding and whether it is monospaced.
EndOfLine represents the end of a line in a string for purposes of matching in StringExpression.
LegendAppearance is an option for charting functions that specifies the appearance of any legends that are generated.
MatrixQ
(Built-in Mathematica Symbol) MatrixQ[expr] gives True if expr is a list of lists or a two-dimensional SparseArray object that can represent a matrix, and gives False otherwise. MatrixQ[expr, test] gives ...
NormalizedSquaredEuclideanDistance[u, v] gives the normalized squared Euclidean distance between vectors u and v.
RawBoxes[boxes] is a low-level construct which is formatted as boxes without further interpretation.
Span
(Built-in Mathematica Symbol) i ;; j represents a span of elements i through j.i ;; represents a span from i to the end.;; j represents a span from the beginning to j.;; represents a span that includes ...
"s_1" <> "s_2" <> ..., StringJoin["s_1", "s_2", ...], or StringJoin[{"s_1", "s_2", ...}] yields a string consisting of a concatenation of the s_i.