This is documentation for Mathematica 5, which was
based on an earlier version of the Wolfram Language.

 Part expr[[i]] or Part[expr, i] gives the i part of expr. expr[[-i]] counts from the end. expr[[0]] gives the head of expr. expr[[i, j, ... ]] or Part[expr, i, j, ... ] is equivalent to expr[[i]] [[j]] ... . expr[[ , , ... ]] gives a list of the parts , , ... of expr. You can make an assignment like t[[i]] = value to modify part of an expression. When expr is a list, expr[[ , , ... ]] gives a list of parts. In general, the head of expr is applied to the list of parts. You can get a nested list of parts from expr[[, , ... ]]. Each part has one index from each list. If any of the are All, all parts at that level are kept. expr[[All, i]] effectively gives the i column in expr. Notice that lists are used differently in Part than in functions like Extract, MapAt and Position. expr[[ Range[i, j] ]] can be used to extract sequences of parts. If expr is a SparseArray object, expr[[... ]] gives the parts in the corresponding ordinary array. In StandardForm and InputForm, expr[[spec]] can be input as exprspec. and can be entered as [[ and ]] or \[LeftDoubleBracket] and \[RightDoubleBracket]. In StandardForm, expr[[spec]] can be input as or See Section 1.2.4, Section 1.2.4, Section 1.4.7, Section 1.8.4, Section 2.1.4 and Section 2.4.2. See also: First, Head, Last, Extract, Position, ReplacePart, MapAt, Take, PadLeft. Related package: LinearAlgebra`MatrixManipulation`. New in Version 1; modified in 5.0.