This is documentation for Mathematica 7, which was
based on an earlier version of the Wolfram Language.
View current documentation (Version 11.1)


is an option for Dynamic, DynamicModule, Manipulate and related constructs, which specifies an expression to be evaluated when the construct is first used or displayed.
  • The typical usage is Initialization:>expr.
  • Initialization expressions defined in particular cells in a notebook are evaluated when those cells are first made visible, and not necessarily when the notebook is first opened.
New in 6