5 External tourism agencies (public and private sector) that try to influence tourism.
6 Other tourism-related externalities, such as alternative tourism destinations that aspect a destination's ability
to attract travellers.
7 Non-tourism-related externalities, or macro-environ mental forces, such as changing political, economic or
social conditions, war, natural disaster, that aspect people's ability to travel.
8 Outputs from the system } both desired and undesired.
9 Rogues or Chaos makers who can push a system to the edge of chaos.