states {activity, nt_action, internal_state, time: TYPE;}: CONTEXT =
BEGIN
states: TYPE = [# activ: activity, basic:internal_state, 
action_time: [nt_action  -> time] #];
states1: TYPE = [# nta:nt_action, is: internal_state, a: activity #];
states2: TYPE = [# nta:nt_action, a: activity #];
END