RFC 2838 (rfc2838) - Page 2 of 6

Uniform Resource Identifiers for Television Broadcasts

RFC 2838                 URIs for TV Broadcasts                 May 2000


3.1. Scheme-only form

   A simplest form of the "tv:" URI scheme is used to refer to the
   "current" or "default" channel:

        tv:

   This URI refers to whichever television broadcast is currently being
   received by the device. It is often used in combination with HTML
   content that is actually being broadcast along with the audio and
   video, where the meaning of "current broadcast" is quite unambiguous
   (because it is the broadcast along with which the content containing
   the URI was received). This is in fact the most common usage of the
   "tv:" scheme today, and is explicitly referenced by the recently
   published specification of the Advanced Television Enhancement Forum
   [ATVEF 1.1].

3.2 DNS-style identifiers

   Television broadcasts traditionally have been identified in a variety
   of ways.  All terrestrial television broadcasters are assigned call
   signs (such as "KDKA" or "WQED") to identify their signal. These are
   generally assigned by national authorities (such as the Federal
   Communications Commission in the United States) and are world unique.
   The global namespace is managed by the International
   Telecommunications Union, which assigns portions to member countries
   (see [ITU RR]).

   Many modern television networks are not broadcasted over-the-air, but
   available only through cable or satellite subscriptions.  The
   identifiers for these networks (such as the familiar "CNN" and "HBO")
   are not regulated at this time.  In some countries, even over-the-air
   broadcasters use these sorts of identifiers, rather than call signs.

   Unfortunately, these two namespaces overlap, with most network
   identifiers also being valid call signs.  Furthermore, network
   identifiers are not world unique, and many cases exist of name
   collisions.  (For example, both the Australian Broadcast Corporation
   and the American Broadcasting Company identify themselves as "ABC".)
   In order to ensure uniqueness, the "tv:" scheme uses DNS-style
   identifiers for all broadcast streams.  Because these build on the
   existing registration system for DNS hostname, all name collisions
   can be resolved through the existing DNS dispute resolution
   processes.







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