- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Mon, 17 Oct 2005 09:32:58 -0400 (EDT)
- To: ben@mit.edu
- Cc: semantic-web@w3.org, public-rdf-in-xhtml-tf@w3.org
From: Ben Adida <ben@mit.edu> Subject: Question from the RDF-in-XHTML task force on the HTML Role Attribute Date: Mon, 17 Oct 2005 08:09:46 -0400 > Hi SWIG members, > > The RDF-in-XHTML Task Force is facing an issue on which we could use > the opinion of more RDF experts. > > Specifically, we're considering assigning a RDF property to the ROLE > attribute in HTML, for example: > > ========== > <div role="dcterms:abstract"> > .... the summary of the document.... > </div> > ========== > > would yield a triple: > > ========== > _:div0 xhtml2:role dcterms:abstract . > ========== > > The question is, what should xhtml2:role be? Should it be simply > rdf:type? Should it be xhtml2:role with no relationship to rdf:type? > How should we go about making this decision? Are there guidelines for > subclassing rdf:type? > > Thanks for your help, > > -Ben Adida > Chair, RDF-in-XHTML Task Force Interesting question. I did a Google search for "html role attribute" and the highest-ranked document was http://www.sagehill.net/docbookxsl/GraphicSelection.html. This document has the following use of role: <mediaobject id="MousePicture"> 1 <imageobject role="html"> 2 <imagedata format="PNG" fileref="mouse.png"/> 3 </imageobject> <imageobject role="fo"> <imagedata format="PDF" fileref="mouse.pdf"/> </imageobject> </mediaobject> Making xhtml2:role be rdf:type, or a subclass of rdf:type, would have the effect of making html and fo both be classes. Do you really want to have a class for html and a class for fo? I then found the normative section for the role attribute, in XHTML2! I enclose the entire section: > 25.2. Role Collection > > role = QName > This attribute describes the relationship the current element (and its > contents) has to the value of the about attribute or its default value. It > is used by applications and assistive technologies to determine the purpose > of UI widgets. In the case of a web page it may be declarative as a > function of particular elements or it may be an attribute which is > configurable by the page author. Additionally, role information may be used > to define each action which may be performed on an element. This allows a > user to make informed decisions on which actions may be taken on an element > and activate the selected action in a device independent way. > > Example > > <nl role="wai:sitemap"> > <li href="downloads">Downloads</li> > <li href="docs">Documentation</li> > <li href="news">News</li> > </nl> > > Additional roles may be defined through the use of this attribute. Roles > shall be defined as qnames referencing RDF definitions for them. The RDF > definition can be used define what the object is, how you would interact > with it, how it relates to other elements, and what other objects it is > like or sub classes. This defines the basis for taxonomies defined amongst > common sets of document elements. For example, dynamic web content often > recreates GUI widgets using combinations of web page elements, style > sheets, and script thus applying different meaning to the elements. This > has benefits for the intraction between web content, user agents, and > assistive technologies by providing for a discoverable interaction > model. For example, this model can be used to allow a screen reader to > provide a speech interface based on real semantics. The user agent could > use the information to create device navigation mappings. > > Authors may use the following relationship names, listed here with their > conventional interpretations. User agents, search engines, etc. may > interpret these relationships in a variety of ways. For example, user > agents may provide access to linked documents through a navigation bar. > > Users may extend this collection of relationships. However, extensions must > be defined in their own namespace, and the relationship names must be > referenced in documents as qualified names (e.g., dc:creator for the Dublin > Core "creator" relationship). > > The following attributes will be standard. They are designed to define > pertinent parts of a document for the purpose of accessibility. User agents > may incorporate device equivalents, such as key mappings in the case of a > desktop user agent, to navigate to these sections of a document. > > main > This defines the main content of a document. > secondary > This is any unique section of the document. In the case of a portal, > this may include but not be limited to: show times; current weather; or > stocks to watch. > navigation > This is the navigation bar on a web document. This is typically a list > of links to other pages on the site or other areas of the same > document. > banner > A banner is usually defined as the advertisement at the top of a web > page. The banner content typically contains the site or company logo > and other key advertisements for the site. > contentinfo > This is information about the content on the page. For example, > footnotes, copyrights, links to privacy statements, etc. would belong > here. > note > The content is parenthetic or ancillary to the main content of the > resource. > seealso > Indicates that the element contains content that is related to the main > content of the page. > search > This is the search section of a web document. This is typically a form > used to submit search requests about the site or is a more general > Internet wide search service. I had a very hard time making even partial sense out of this. The about attribute is used in meta elements, and may have no relationship to the current element. I don't believe that there is any notion of an "RDF definition" in the RDF documents. I submit that before determining whether role maps to rdf:type or not, that the RDF-in-XHTML spend some time trying to get a comprehensible normative section for the use of role in XHTML2. In any case, it appears that role provides a three-way relationship where its attribute value is the property. This makes it seem as if the triple in the first use of role above should be ? html ? and not ? xhtml2:role html (In this I agree with Pete Johnston.) Peter F. Patel-Schneider
Received on Monday, 17 October 2005 13:33:14 UTC