Index generation method, index generation apparatus, index addition system, and program and storage medium thereof

An index generation method comprising the steps of:

• defining, in advance, basic index information concerning an index that constitutes data that describes contents including a set of triggering actions;
• and generating said index by employing operating procedures that use said basic index information, wherein information relative to a triggering action for the generation of an index and information concerning a timespan for said index are defined for said basic index information wherein said basic index information defines information concerning a hierarchy of at least one higher triggering action related to a lower triggering action such that said lower triggering action comes within said higher triggering action for a single triggering index that is formed for a single lower triggering action, and wherein a higher index covering said higher triggering action is added when the lower index covering said lower triggering action is added.