12. The temporal formatting method of claim 11 further including operating the processor to identify as having unpredictable behavior each respective media item segment indicating an unpredictable occurrence or an unpredictable media segment duration; and operating the processor to produce a second schedule data structure including a presentation command for each media item segment indicating unpredictable behavior; the presentation command indicating an unresolved document presentation time assigned to a starting event in a media item segment having an unpredictable occurrence; the presentation command further indicating an unresolved document presentation time assigned to an ending event in a media item segment having an unpredictable duration.
12. The temporal formatting method of claim 11 further including operating the processor to identify as having unpredictable behavior each respective media item segment indicating an unpredictable occurrence or an unpredictable media segment duration; and operating the processor to produce a second schedule data structure including a presentation command for each media item segment indicating unpredictable behavior; the presentation command indicating an unresolved document presentation time assigned to a starting event in a media item segment having an unpredictable occurrence; the presentation command further indicating an unresolved document presentation time assigned to an ending event in a media item segment having an unpredictable duration. 13. The temporal formatting method of claim 12 further including operating the processor to assign document presentation times to the unresolved document presentation times in the second schedule data structure at the time the time-dependent document is presented under the control of the first schedule data structure; the first and second schedule data structures together controlling presentation of media items having predictable and unpredictable behavior in the time-dependent document.