[1] Its predominant use is in support of streaming media applications, such as voice over IP (VoIP) and video conferencing.
The IETF published the original specification as a Proposed Standard in April 1998 (RFC 2327).
Its name is "SDP Seminar" and extended session information ("A Seminar on the session description protocol") is included along with a link for additional information and an email address to contact the responsible party, Jane Doe.
The first is an audio stream on port 49170 using RTP/AVP payload type 0 (defined by RFC 3551 as PCMU), and the second is a video stream on port 51372 using RTP/AVP payload type 99 (defined as "dynamic").
Finally, an attribute is included which maps RTP/AVP payload type 99 to format h263-1998 with a 90 kHz clock rate.
It is intended to be distributed over different transport protocols as necessary, including SAP, SIP, and RTSP.
Attributes can appear within the Session or Media sections and are scoped accordingly as session-level or media-level.
[6] Attributes are either properties or values: Two of these attributes are specially defined: In both cases, text fields intended to be displayed to a user are interpreted as opaque strings, but rendered to the user or application with the values indicated in the last occurrence of the fields charset and sdplang in the current media section, or otherwise their last value in the session section.
NTP supports this with field z, which indicates a series of pairs whose first item is the NTP absolute time when a daylight adjustment will occur, and the second item indicates the offset to apply relative to the absolute times computed with the field r. For example, if a daylight adjustment will subtract 1 hour on 31 October 2010 at 3 am UTC (i.e. 60 days minus 7 hours after the start time on Sunday 1 August 2010 at 10am UTC), and this will be the only daylight adjustment to apply in the scheduled period which would occur between 1 August 2010 up to the 28 November 2010 at 10 am UTC (the stop time of the repeated 1-hour session which is repeated each week at the same local time, which occurs 88 days later), this can be specified as: If the weekly 1-hour session was repeated every Sunday for one full year, i.e. from Sunday 1 August 2010 3 am UTC to Sunday 26 June 2011 4 am UTC (stop time of the last repeat, i.e. 360 days plus 1 hour later, or 31107600 seconds later), so that it would include the transition back to Summer time on Sunday 27 March 2011 at 2 am (1 hour is added again to local time so that the second daylight transition would occur 209 days after the first start time): As SDP announcements for repeated sessions should not be made to cover very long periods exceeding a few years, the number of daylight adjustments to include in the z= parameter should remain small.