A data delivery mechanism, such as a recordable disk or packets on a wire, delivering an info segment which specifies interruption points at which a first content item such as a television program is to be interrupted and a second content item such as an advertisement is to be inserted. The info segment may prevent certain types of second content items from being utilized, may permit them to be avoided, may control their duration, and other aspects of their utilization. The info segment may specify with which first content item it is associated. Other embodiments are also disclosed and claimed, such as an electronic programming guide.