Branching space-time, postprint january, 2003

``Branching space-time'' is a simple blend of relativity and indeterminism. Postulates and definitions rigorously describe the ``causal order'' relation between possible point events. The key postulate is a version of ``everything has a causal origin''; key defined terms include ``history'' and ``choice point.'' Some elementary but helpful facts are proved. Application is made to the status of causal contemporaries of indeterministic events, to how ``splitting'' of histories happens, to indeterminism without choice, and to Einstein-Podolsky-Rosen distant correlations.