Example
<startTime>20020701T00:00:00.001Z</startTime> <endTime>20021030T00:00:00.001Z</endTime>
Places this can be found
channelEffectiveTimeOverlap contains this directly
networkEffectiveTimeOverlap contains this directly
siteEffectiveTimeOverlap contains this directly
stationEffectiveTimeOverlap contains this directly