This is documentation for Mathematica 6, which was
based on an earlier version of the Wolfram Language.
 Parts of Expressions Mathematica's unified symbolic architecture allows immediate generalization of part-oriented list operations to arbitrary expressions—supporting operations both on individual parts, and on collections of parts at specified levels in expression trees. Part (..[[..]]) get any part of an expression (reset with =) ReplacePart — replace numbered parts of an expression      Position — find the positions of any pattern in an expression Cases — find cases of any pattern in an expression      MapAt — apply a function at particular positions in an expression Map (/@) — apply a function at specified levels in an expression MapAll (//@) — apply a function to all parts of an expression      Heads — option for specifying whether to include heads      Sow, Reap — collect parts "sown" inside of an expression TUTORIALS Parts of Expressions Adding, Removing and Modifying List Elements Manipulating Lists by Their Indices Applying Functions to Parts of Expressions MORE ABOUT Parts of Lists & Arrays Formula Manipulation