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Re: Technique for Attribute Access

From: Charles McCathieNevile <charles@w3.org>
Date: Thu, 6 May 1999 10:40:22 -0400 (EDT)
To: Jon Gunderson <jongund@staff.uiuc.edu>
cc: Harvey Bingham <hbingham@ACM.org>, w3c-wai-ua@w3.org
Message-ID: <Pine.LNX.4.10.9905061036510.3421-100000@tux.w3.org>
There are two things at work here. The first is to allow access to the
attributes (propoerties) of a given element. The second is to search for an
element with a given property (attribute value).

I think both are of value, and if available together would satisfy the 'allow
a user to find the next thing like this' checkpoint.

I am using 'properties' here as information pertaining to an object, rather
than the more restricted definition used in the document, which only refers
to style properties. I suggest that the definition in general be expanded,
and the term 'style properties' be used when that is what is meant.

Charles McCN

On Thu, 6 May 1999, Jon Gunderson wrote:

  Thanks for the quick posting Harvey.  
  
  Could we change the name of the checkpoint to:
  Checkpoint: Allow the user to search for an element by its attribute values
  Subgroup: dependent user agents
  Priority: 3
  
  
  At 05:57 PM 5/5/99 -0400, you wrote:
  >Per our discussion today, here's a possible checkpoint and technique.
  >
  >Checkpoint: Allow the user to learn of attributename="value" pairs for any
  >element. 
  >Priority: 3
  >
  >Technique: 
  >The meta-information about an element contained in attribute values can 
  >support the understanding of the containing element, or its descendents.
  >It should be exposable by user request.
  >
  >Details: 
  >
  >Many attributes are implicitly present, so the presence in an element of an 
  >attribute=value pair cannot be depended upon for information. It is up to
  the 
  >semantic description of each attribute name and its allowed values for an 
  >element type to indicate both the explicit meaning of the attribute, and
  what 
  >is the defaulting meaning of a missing attribute. Often this meaning can be 
  >determined from the value of the same-named attribute on an ancestor element.
  >Other times the semantics indicate no inheritance (e.g., an id, a document-
  >unique identifier for referencing a particular element). 
  >
  >Some attributes are generally applicable to all or most element types. For 
  >these, common understanding of their use is reasonable to expect for authors 
  >and users. 
  >
  >Search on attributename and possibly value is important. Search may be on 
  >the next attributename, or on attribute value, possibly inherited, possibly 
  >qualified by element name. 
  >
  >Each search returns the next occurrence of the containing element. An 
  >implementation possibility is to list all matches, and return them in 
  >order to the user.
  >
  >Another useful result is to learn the different attributename="value" pairs 
  >or a subset of them for any particular element.
  >
  >Another useful search is to find the next element that can have a particular 
  >attributename, and for it seeking its default value, possibly from the 
  >nearest ancestor.
  >
  >Details for HTML 4.0: These common attributes are associated with almost 
  >all HTML 4.0 element types, and can be learned: 
  >
  >% attrs
  >  "%coreattrs; %i18n; %events;"
  >
  >including:
  > 
  >% coreattrs
  > "id          ID             #IMPLIED -- document-wide unique id --
  >  class       CDATA          #IMPLIED -- space separated list of classes --
  >  style       %StyleSheet;   #IMPLIED -- associated style info --
  >
  >    ELEMENT TYPES WITHOUT %attrs; but with %coreattrs
  >        BDR  -- bi-directional override--
  >        BR   -- forced line break --
  >        HR   -- horizontal rule --
  >
  >% i18n
  >  lang        %LanguageCode; #IMPLIED -- language code --
  >  dir         (ltr|rtl)      #IMPLIED -- direction for weak/neutral text --"
  >
  >    ELEMENT TYPES WITHOUT %attrs; but with %i18n; 
  >        HTML, HEAD   -- lang, dir defaults for document --
  >        META, TITLE  -- lang, dir, for use with content --
  >        STYLE        -- lang, dir, for use with title in HEAD --
  >    
  >% events;
  > "onclick     %Script;       #IMPLIED -- a pointer button was clicked --
  >  ondblclick  %Script;       #IMPLIED -- a pointer button was double
  clicked--
  >  onmousedown %Script;       #IMPLIED -- a pointer button was pressed down --
  >  onmouseup   %Script;       #IMPLIED -- a pointer button was released --
  >  onmouseover %Script;       #IMPLIED -- a pointer was moved onto --
  >  onmousemove %Script;       #IMPLIED -- a pointer was moved within --
  >  onmouseout  %Script;       #IMPLIED -- a pointer was moved away --
  >  onkeypress  %Script;       #IMPLIED -- a key was pressed and released --
  >  onkeydown   %Script;       #IMPLIED -- a key was pressed down --
  >  onkeyup     %Script;       #IMPLIED -- a key was released --"
  >
  >    ELEMENT type without %attrs; but with %events; (and %coreatts;)
  >        HR -- horizontal rule, takes space, has no text --
  >
  >    ELEMENT types with none of %attrs;, %coreatts;, %i18n;, or %events;
  >        PARAM
  >        BASE
  >        SCRIPT
  >
  >Some attribute names are used in consistent ways, as reflected by their
  comments. A few seem
  >to have different semantics. The latter should be avoided, particularly
  where inheritance
  >of attribute value is presumed.
  >
  >For XML applications, a similar set of general attributes may be useful. A
  common occurrence
  >is to specialize a general element name to indicate a local variation on
  the general
  >element type. For example, in electronic books, different books have
  different names for
  >the hierarchic sectioning. Some use chapter, some use part, some use
  section, some use "El Parto".
  >
  >Regards/Harvey Bingham
  >
  >
  >    
  > 
  Jon Gunderson, Ph.D., ATP
  Coordinator of Assistive Communication and Information Technology
  Division of Rehabilitation - Education Services
  University of Illinois at Urbana/Champaign
  1207 S. Oak Street
  Champaign, IL 61820
  
  Voice: 217-244-5870
  Fax: 217-333-0248
  E-mail: jongund@uiuc.edu
  WWW:	http://www.staff.uiuc.edu/~jongund
  	http://www.als.uiuc.edu/InfoTechAccess
  

--Charles McCathieNevile            mailto:charles@w3.org
phone: +1 617 258 0992   http://www.w3.org/People/Charles
W3C Web Accessibility Initiative    http://www.w3.org/WAI
MIT/LCS  -  545 Technology sq., Cambridge MA, 02139,  USA
Received on Thursday, 6 May 1999 10:40:26 GMT

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