As per Relevance of the word identifier, we have this rfc below:
Network Working Group D.
Request for Comments: 2838 WebTV Networks, Inc
Category: Informational M.
Liberate Technologies, Inc
May 2000
Uniform Resource Identifiers for Television
Status of this
This memo provides information for the Internet community. It
not specify an Internet standard of any kind. Distribution of
memo is unlimited
Copyright
Copyright (C) The Internet Society (2000). All Rights Reserved
1.
World-Wide Web browsers are starting to appear on a variety
consumer electronic devices, such as television sets and
set-top boxes, which are capable of receiving television
from either terrestrial broadcast, satellite broadcast, or cable.
this context there is a need to reference television broadcasts
the URI format described in [RFC 2396]. This document describes
widely-implemented URI scheme to refer to such broadcasts
2. Television
The basic structure of a television URI is
tv:<broadcast
where broadcast is a description of the data source. The
takes the form of a DNS-style identifier for a particular
or television network. For example
tv:wqed.org the WQED
tv:nbc.com the NBC
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RFC 2838 URIs for TV Broadcasts May 2000
3.1. Scheme-only
A simplest form of the "tv:" URI scheme is used to refer to
"current" or "default" channel
tv
This URI refers to whichever television broadcast is currently
received by the device. It is often used in combination with
content that is actually being broadcast along with the audio
video, where the meaning of "current broadcast" is quite
(because it is the broadcast along with which the content
the URI was received). This is in fact the most common usage of
"tv:" scheme today, and is explicitly referenced by the
published specification of the Advanced Television Enhancement
[ATVEF 1.1].
3.2 DNS-style
Television broadcasts traditionally have been identified in a
of ways. All terrestrial television broadcasters are assigned
signs (such as "KDKA" or "WQED") to identify their signal. These
generally assigned by national authorities (such as the
Communications Commission in the United States) and are world unique
The global namespace is managed by the
Telecommunications Union, which assigns portions to member
(see [ITU RR]).
Many modern television networks are not broadcasted over-the-air,
available only through cable or satellite subscriptions.
identifiers for these networks (such as the familiar "CNN" and "HBO")
are not regulated at this time. In some countries, even over-the-
broadcasters use these sorts of identifiers, rather than call signs
Unfortunately, these two namespaces overlap, with most
identifiers also being valid call signs. Furthermore,
identifiers are not world unique, and many cases exist of
collisions. (For example, both the Australian Broadcast
and the American Broadcasting Company identify themselves as "ABC".)
In order to ensure uniqueness, the "tv:" scheme uses DNS-
identifiers for all broadcast streams. Because these build on
existing registration system for DNS hostname, all name
can be resolved through the existing DNS dispute
processes
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RFC 2838 URIs for TV Broadcasts May 2000
In the simplest form, domain names themselves are used as
identifiers. For example
tv:abc.com the American Broadcast
tv:abc.co.au the Australian Broadcast
In some cases, networks have multiple broadcast streams that need
be distinguished. This is also handled in DNS style
tv:east.hbo.com HBO
tv:west.hbo.com HBO
It is important to note that these DNS-style identifiers need
match real hostnames; they should not be resolved to IP
using DNS. Thus, using the terms as defined in RFC 2396, the "tv:"
scheme is a Uniform Resource Identifier and not a Uniform
Locator
In order to support these identifiers in a "tv:" URI, a receiver
implement a means to map known identifiers to frequencies. The
of this map and the way in which it is used are currently browser
and device-specific and are beyond the scope of this document.
this way, the "tv:" scheme is somewhat analogous to the "news:"
"file:" schemes in [1]: it merely names a television broadcast
but assumes that the local browser has some means for
retrieving that signal on the local device. A variety of
systems currently provide device-specific mappings from
identifiers to specific channel numbers or directly to frequencies
These systems can be incorporated into television sets or set-
boxes to facilitate the interpretation of television URIs by
client device
3.3 Obsolete
Previous drafts of this specification allowed broadcasts to
identified by channel numbers, such as "tv:4", and this form
currently supported by several independent platforms. The
numbers generally correspond to tuning frequencies in the
national broadcast frequency standards; for example, "tv:4" in
United states would be found at 66 MHz. However, because
mapping of channel numbers to frequencies varies from country
country, this form is particularly ill-suited to use on the Internet
Previous drafts also allowed network identifiers and call signs to
used directly as broadcast identifiers, as in "tv:abc" and "tv:kron".
These forms should not be used because of the name collision
described in the previous section
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RFC 2838 URIs for TV Broadcasts May 2000
4. BNF for Television
The following is a formal specification for the new URIs
tvuri = "tv:" [ broadcast ]
broadcast = dns-
dns-identifier = *( domainlabel "." ) toplabel [ "." ]
domainlabel = alphanum | alphanum *( alphanum | "-" )
toplabel = alpha | alpha *( alphanum | "-" )
The definitions of alpha and alphanum are from [RFC 2396].
Furthermore, the definition of dns-identifier is identical to
definition of hostname in RFC 2396, and is case-insensitive
5.
Many of the ideas in this document came out of conversations
Andrew Lochart. Other people who supplied valuable input include
Trifiro and Eric Del Sesto. The original draft of this URI
was developed while the author was at Wink Communications.
recent suggestions have come from Lee Acton, Jonathan Boltax,
Blackketter, Michael Dolan, Iain Hackett, Jim Helman, Sean McDowell
David Mott, Scott Watson, and others in the ATVEF Technical
Group (which the authors co-chaired), and from Craig Finseth,
Thomas, Harald Alvestrand, and Larry Masinter
6. Security
This new URI scheme is subject to the same security implications
the general URI scheme described in [RFC 2396]. It is possible
the mere act of viewing a television broadcast signal may cause
to be incurred to the viewer in some instances (e.g., "pay-per-view
movies and events). Any software that uses this URI scheme to
automatic tuning of a client device to a particular
broadcast signal should alert users before performing actions
may incur costs to the user
7.
[RFC 2396] Berners T., Fielding, R. and L. Masinter, "
Resource Identifiers (URI): Generic Syntax", RFC 2396,
August 1998.
[ATVEF 1.1] Advanced Television Enhancement Forum, "
Television Enhancement Forum Specification
1.1r26," February 1999.
http://www.atvef.com/library/spec1_1a.
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RFC 2838 URIs for TV Broadcasts May 2000
[ITU RR] International Telecommunications Union, "
Regulations," 1998. See especially Article S19,
"Identification of stations," and Appendix S42, "Table
allocation of international call sign series."
9. Authors'
Dan
WebTV Networks, Inc
1065 La
Mountain View, CA 94043
EMail: djz@corp.webtv.
Mark
Liberate
2 Circle Star
San Carlos, CA 94070
EMail: mav@liberate.
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RFC 2838 URIs for TV Broadcasts May 2000
10. Full Copyright
Copyright (C) The Internet Society (2000). All Rights Reserved
This document and translations of it may be copied and furnished
others, and derivative works that comment on or otherwise explain
or assist in its implementation may be prepared, copied,
and distributed, in whole or in part, without restriction of
kind, provided that the above copyright notice and this paragraph
included on all such copies and derivative works. However,
document itself may not be modified in any way, such as by
the copyright notice or references to the Internet Society or
Internet organizations, except as needed for the purpose
developing Internet standards in which case the procedures
copyrights defined in the Internet Standards process must
followed, or as required to translate it into languages other
English
The limited permissions granted above are perpetual and will not
revoked by the Internet Society or its successors or assigns
This document and the information contained herein is provided on
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED,
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
Funding for the RFC Editor function is currently provided by
Internet Society
Zigmond & Vickers Informational [Page 6]
if you see any problems within the linking, don't worry be happy,
this is version 0.1 of the Relevance System and you gotta expect some crappy subroutines sometimes,
just be content we did not write this in Java, which would have made this "bigger and better" HAHAHHA.
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