Sessions may either be bounded or unbounded in time. Whether or not they are bounded, they may be only active at specific times.
SDP can convey an arbitrary list of start and stop times bounding the session. For each bound, repeat times such as ``every Wednesday at 10am for one hour'' can be specified.
This timing information is globally consistent, irrespective of local time zone or daylight saving time because it is given in UTC. Modifiers can be specified to uniquely apply offsets if the session crosses a change to or from daylight saving time.