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Specification: http://www.whatwg.org/specs/web-apps/current-work/multipage/microdata.html Multipage: http://www.whatwg.org/C#attr-itemid Complete: http://www.whatwg.org/c#attr-itemid Comment: Explain the point of itemid Posted from: 83.218.67.122 by philipj@opera.com User agent: Opera/9.80 (X11; Linux x86_64; U; Edition Next; en) Presto/2.9.186 Version/12.00
http://www.brucelawson.co.uk/2011/microdata-help-please/ The spec doesn't do a good job of explaining why anyone would ever want to use itemid, deferring completely to the vocabulary. It would be nice for curious minds to get some kind of clue why the attribute might be useful or if they can safely ignore it.
This is a text proposal. # Current text: Elements with an itemscope attribute and an itemtype attribute that references a vocabulary that is defined to support global identifiers for items may also have an itemid attribute specified, to give a global identifier for the item, so that it can be related to other items on pages elsewhere on the Web. # Proposed text: Elements with an itemscope attribute and an itemtype attribute may also have an itemid attribute specifying a global identifier for the item. The global identifier provide a mechanism to associate related items elsewhere on the Web. # Current text: The exact meaning of a global identifier is determined by the vocabulary's specification. It is up to such specifications to define whether multiple items with the same global identifier (whether on the same page or on different pages) are allowed to exist, and what the processing rules for that vocabulary are with respect to handling the case of multiple items with the same ID. # Proposed text: Vocabulary designers are encouraged to allow global identifier on items. It is up to such specifications to define whether multiple items with the same global identifier (whether on the same page or on different pages) are allowed to exist, and what the processing rules for that vocabulary are with respect to handling the case of multiple items with the same ID. Content authors should use global identifiers, when encouraged by the vocabulary specification, to allow vocabulary parsers to associate items across the Web. Reusing well known identifiers is also encouraged. ------------- Note I removed: "The exact meaning of a global identifier is determined by the vocabulary's specification." because it is a false statement. A book vocabulary may say you should use for the value of itemid, URIs of the type "urn:isbn:" for global identifiers on items. But it doesn't define the meaning of urn:isbn:123456789.
EDITOR'S RESPONSE: This is an Editor's Response to your comment. If you are satisfied with this response, please change the state of this bug to CLOSED. If you have additional information and would like the editor to reconsider, please reopen this bug. If you would like to escalate the issue to the full HTML Working Group, please add the TrackerRequest keyword to this bug, and suggest title and text for the tracker issue; or you may create a tracker issue yourself, if you are able to do so. For more details, see this document: http://dev.w3.org/html5/decision-policy/decision-policy.html Status: Rejected Change Description: no spec change Rationale: There's a whole section on itemid="". I don't understand the problem here. I can't tell you what it means, it's entirely up to the vocabulary. It's like asking what id="" means. It's just a global identifier. How you use it is up to the author (in the case of id="") or the vocabulary (in the case of itemid=""). (In the WHATWG copy I've tried to clarify what the global identifier means for vCard and vEvent; that doesn't affect the W3C subset of the spec. Diff below.)
Checked in as WHATWG revision r6344. Check-in comment: I forgot to include the text for UID in the bit about global identifiers. http://html5.org/tools/web-apps-tracker?from=6343&to=6344
(In reply to comment #3) > Rationale: There's a whole section on itemid="". I don't understand the problem > here. It is not about redefining itemid but about clarifying the role. Your statement for closing is true but completely orthogonal to what was suggested. > I can't tell you what it means, it's entirely up to the vocabulary. This is unrelated to the issue explained here. > It's > like asking what id="" means. It's just a global identifier. We all agree on that. Not the issue. The proposed text are about giving information on how itemid are used in the context of microdata. There is also still a false statement in the current specification. "The exact meaning of a global identifier is determined by the vocabulary's specification." something along "the specific types of uris usable as a global identifier is determined by the vocabulary's specification." would be correct.
mass-move component to LC1