15. The apparatus 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 apparatus 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. 18. The apparatus of claim 15 wherein the processor is further configured to test at least one of the derived features against at least one of the applicability conditions associated with a story angle of the angle set data structure to determine whether at least one applicability condition for at least one story angle has been satisfied by the processed data.