Re: [VCARDDAV] UID - why singular, not plural/ multiple?

"Andy Mabbett" <> Sun, 25 July 2010 13:45 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 011023A694E for <>; Sun, 25 Jul 2010 06:45:40 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -5.299
X-Spam-Status: No, score=-5.299 tagged_above=-999 required=5 tests=[AWL=1.300, BAYES_00=-2.599, RCVD_IN_DNSWL_MED=-4]
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id FrDkHJYF8emN for <>; Sun, 25 Jul 2010 06:45:38 -0700 (PDT)
Received: from ( []) by (Postfix) with ESMTP id F15D03A6905 for <>; Sun, 25 Jul 2010 06:45:37 -0700 (PDT)
Received: from ([] country=GB ident=andy^pop3*pigsonthewing#org*uk) by with esmtpa (Gradwell gwh-smtpd 1.290) id 4c4c4013.733a.3b for; Sun, 25 Jul 2010 14:45:55 +0100 (envelope-sender <>)
Received: from (SquirrelMail authenticated user by with HTTP; Sun, 25 Jul 2010 14:45:56 +0100
Message-ID: <>
In-Reply-To: <>
References: <> <>
Date: Sun, 25 Jul 2010 14:45:56 +0100
From: "Andy Mabbett" <>
User-Agent: SquirrelMail/1.4.19
MIME-Version: 1.0
Content-Type: text/plain;charset=iso-8859-1
Content-Transfer-Encoding: 8bit
X-Priority: 3 (Normal)
Importance: Normal
Subject: Re: [VCARDDAV] UID - why singular, not plural/ multiple?
X-Mailman-Version: 2.1.9
Precedence: list
List-Id: IETF vcarddav wg mailing list <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Sun, 25 Jul 2010 13:45:40 -0000

On Sun, July 25, 2010 13:33, Simon Perreault wrote:
> Andy Mabbett wrote, on 07/25/2010 02:23 PM:
>> For example, UIDs for the playwright William Shakespeare include:
>>    *
>>    *
>>    *
>>    *
>>    *   ...
>> Have I misunderstood the purpose of UID?
> Yes, I think you did. The above are not UIDs, they are locators. Pretty
> much like the difference between URL and URN.

My assumption was derived from this description in the hCard microformat

   UID in vCard simply becomes another semantic applied
   to a specific URL (or EMAIL) for an hCard.

and this, from an appendix to that spec:

   In addition, such link(s) in hCards to the canonical URL for
   a person on that site should also have the classname of "uid".

Together with this from the same appendix:

   <a rel="me" class="url uid" href="">
     Flickr profile

   Such a "url" + "uid" property could also be used by a site as
   that person's OpenID URL.

Similar examples are given on:

Perhaps that section should include reference to an RFC (or other
resource) which defines UID in the strict sense meant there?

> If you make up an example involving vCards I'll be glad to explain it
> further...

Thank you; I'll do more reading before I trouble you further on that point.

However, should we not consider (not least given the growing importance of
linked data) a vCard property for URLs which act as identifiers (in the
looser sense, such as the Shakespeare examples above), as opposed to the
URL of the subject's own website? The use of such URLs would facilitate a
greater amount of matching, even in cases where UIDs are not available.

Andy Mabbett