RE: Where are we?

From: Dan Zigmond (
Date: Mon, Oct 11 1999

Message-ID: <15AAE0EBDCC9D1119FFA00805F85642E04CFABDE@WNI-MSG-02>
From: Dan Zigmond <>
To: "'Harald Tveit Alvestrand'" <>,
Cc: Dean Blackketter <>
Date: Mon, 11 Oct 1999 10:29:14 -0700
Subject: RE: Where are we?

One of my colleagues, Dean Blackketter, has been working on a system for
describing time periods using the URI fragment syntax.  This seems like a
fairly natural extension of the notion of fragment into the time domain,
since in a sense what you're asking for is a way to specify that fragment of
a television stream that contains the material broadcasted at a particular

I'll let Dean post a more complete specification, but the basic syntax uses
ISO-8601 time formats and looks something like this:

which represents whatever is on PBS between 1PM and 1:30 today.  I've made
this unnecessarily long just as an example; in 8601 you can drop the
trailing zeros, and the date itself is optional.  I think 8601 is a pretty
complete and flexible representation of time, so leveraging it makes the
problem a lot simpler than having to make something up.

As has been pointed out, this is a fundamentally different problem than URIs
for specific programs on television, which should be independent of both
network and time.


Dan Zigmond 
Senior Manager, Broadcast Applications 
WebTV Networks, Inc. 

-----Original Message-----
From: Harald Tveit Alvestrand []
Sent: Saturday, October 09, 1999 3:00 PM
To: Dan Zigmond; 'Scott J. Anderson';
Subject: RE: Where are we?

At 09:31 08.10.99 -0700, Dan Zigmond wrote:
>The goal here is to define a URI scheme for streams of television broadcast
>content (i.e., networks or stations or channels) rather than for individual
>pieces of content (programs).  So there would be a "tv:" URI for PBS
>(""), and for local member stations of PBS like WQED
>(""), but not for individual pieces of programming that happen
>air on PBS.  I see the latter as a different problem.  Important, yes, but

1) I like the proposed scheme of using the DNS namespace.
2) As a TV watcher, when I've identified a channel, the next level of 
identification is commonly a timeslot, as is done by the ShowView 
bizarre-digit scheme here in Norway, for instance.
I would regard content as being an orthogonal identifier, but timeslot 
seems intrinsically channel-bound.

Not that it's simple - see the CALSCH calendar specifications for just how 
complex "every thursday at 9 AM, here in Trondheim" can be to specify 
exactly - but it's a logical extension to a channel/program stream 
identification scheme. (did we ever get down to writing up a glossary for 
this stuff??)

Making sure it's possible to extend the scheme in that direction may be the 
only thing we should do now.

Harald Tveit Alvestrand, Maxware, Norway