The following subsystems comprise the [The Tcl Core%|%Tcl core]:

   * Basic utilities (dynamic strings, hashtables, memory allocator)
   * Value system ([Tcl_Obj], etc.)
   * Multi-precision integer support library
   * Interpreter core (including procedures, variables and traces)
   * Bytecode engine
   * Namespaces
   * Event handler
   * [Tcl Core IO System%|%I/O] and [encoding] engine
   * Virtual Filesystem engine
   * Regular Expression engine
   * Package manager
   * The [clock] command
   * Child interpreter manager
   * Thread support


Note that there are other minor subsystems too (e.g. the [format] and [scan] commands), and that the full list of maintenance areas[http://tip.tcl.tk/16.html] may divide some subsystems into several pieces for ease of maintenance. ''-- [DKF]''

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Various pages dealing with Tcl internals topics include:

   * [History of TCL_EVAL_INVOKE]

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