| 摘要 |
An interactive television trigger has a time attribute value that indicates a future time when the trigger is to be executed. In many situations, the trigger is sent to the receiver unit prior to the future time (e.g., to account for bandwidth limitations or to allow prefetching of an information resource associated with the trigger). Redundant triggers may be sent as the future time draws closer. In this way, if the receiver unit did not receive a previously sent trigger for some reason, a redundant trigger is available for execution. The receiver unit may ignore duplicate triggers. The time attribute value also may indicate a life span during which the trigger is valid so that, if a user switches video channels but returns to a video channel for which execution of the trigger is desired, the trigger may be re-executed during the life span. |
