Hi, I am trying to implement an asynchronous state machine whose states contain substates. Since my compilation errors seem to be related to the statechart library (instead of directly to the code I wrote myself), I started to suspect that the statechart library does not support the nesting of states in an asynchronous state machine. Am I right or am I missing something? Upon trying any combination of boost::statechart::state and boost::statechart::simple_state as the super class of the top-level states and sub states, the typical compilation errors I received are like the following: 'deep_construct' is not a member of 'boost::statechart::simple_state::deep_construct_inner_impl_non_empty::deep_construct_inner_impl (const boost::intrusive_ptr<T>&, typename Context::inner_context_type::outermost_context_base_type&) [with InnerList = boost::mpl::list, MostDerived = robot::RobotSM::CONNECTED_WITH_OPERATOR, Context = robot::RobotSM::RobotSM, InnerInitial = robot::RobotSM::SCOUTING, boost::statechart::history_mode historyMode = (boost::statechart::history_mode)0u]::current_inner' RobotBehavior line 894, external location: /usr/include/boost/statechart/simple_state.hpp C/C++ Problem 'class boost::statechart::simple_state, (boost::statechart::history_mode)0u>' has no member named 'deferred_events' RobotBehavior line 360, external location: /usr/include/boost/statechart/simple_state.hpp C/C++ Problem 'class boost::statechart::state, (boost::statechart::history_mode)0u>' has no member named 'set_context' RobotBehavior line 50, external location: /usr/include/boost/statechart/state.hpp C/C++ Problem If nested states are intentionally not supported in current Boost.Statechart, is there a fundamental reason for this restriction? Or is it just not yet implemented as a feature of asynchronous state machines? Many thanks for your response, in advance. Best regards, Gurcan