15. The computer program product of claim 3 wherein the angle set data structure further comprises data for a plurality of story angles, the story angle data comprising, for each story angle (1) an identifier for that story angle, and (2) data representative of at least one applicability condition for that story angle.
15. The computer program product of claim 3 wherein the angle set data structure further comprises data for a plurality of story angles, the story angle data comprising, for each story angle (1) an identifier for that story angle, and (2) data representative of at least one applicability condition for that story angle. 29. The computer program product of claim 15 wherein at least one of the story angles has an associated applicability condition corresponding to a temporal condition.