Classifying Starships

One way to classify starships is by the sources they use for energy and momentum.  Does the vessel generate energy internally, or does is it supplied after launch or extracted from the environment?  Does the vessel carry its own reaction mass?  This table illustrates different approaches that illustrate different answers to these questions.

Approach	Energy Source	Reaction mass	Example[s]
I/I	Internal	Internal	Classical rocket; Project Orion.
E/E	External	External	Bussard Ramjet using fusion of ISM to accelerate remnants of drive gas away; beamed power used to accelerate ISM
E/I	External	Internal	Energy beamed to vessel is used to accelerate on-board reaction mass to relativistic velocities
I/E	Internal	External	Internal power source (antimatter?) used to accelerate ISM reaction mass to relativistic velocities.
E/mixed	Internal	E/acceleration,I/deceleration	Beamed light pressure on sails to accelerate. To decelerate break into two mirrors and first bounces light back to second slowing it down.

All of these approaches look like they could be feasible (for our somewhat warped view of feasibility) and in future posts we may contemplate the technologies that would favor one over the other. There is some balancing between carrying the energy supply/reaction mass versus the mechanisms to acquire these from the environment or from Earth-based transmissions.