Re: 3.1 b-h: LABEL attributes

At 6:28 PM -0800 3/1/97, Tim Bray wrote:
> Dimension 1: Which pieces of information should be specified for
> possible inclusion in linking elements?
> ...
> e. caption
> ...
>ERB consensus:
> - we will refer to this as a Label, not an explainer or caption
> - there is strong support for having labels.
>However, the ERB is unhappy with allowing only a simple character string;
>how does one support multilingual labeling, or labels which are graphic?
>Our provisional solution is to support both a RESOURCE LABEL attribute and/or
>a RESOURCE LABEL LOCATOR attribute, the latter being used to locate and
>retrieve a structured label.  But then do we need a LABEL LOCATOR
>SCHEME?  Or make it use the same scheme as the resource locator?

If we allow multiple locator schemes, it would be an unreasonable
constraint to make a label locator use the same scheme; I think we'd have
to have a label locator scheme attribute.  If we don't allow multiple
schemes, or (same thing, really) allow them to be self-identifying right
there in the value, no extra attribute is needed.

I think it should be possible to associate a complex label with the
resource by containment in the simple linking element itself, or in the
resource-specific subelement of an xlink.  (Associating a label with the
resource *by linking* is, to me, not a characteristic of a "simple"
link...)  For example, we could allow an XML-knowledgeable label subelement
as follows:

  <!ELEMENT A (label?, ...)>
      XML-LINK    CDATA   #FIXED  "xml-link"
  <!ELEMENT label (english, french?)>
  <!ATTLIST label
      XML-LINK    CDATA   #FIXED  "xml-label"  <!--*New "mapping token"*-->

  <a href="...">
  <english>The first chapter</english>
  <french>Le premiere chapitre</french>  <!--*Probably mangled!*-->
  Click here</a> for...

I don't know how much this complicates things.  For example, would we want
to constrain labels to appear as the *first* content inside the linking
element, so that linear processing could easily pick it up before hitting
the main content of the element?  If we had all kinds of restrictions, it
would hurt more than it helps.  But given the issues that have been brought
up about labels, I do like the idea of being able to structure your
labeling information any way you like, using the full power of an
eXtensible Markup Language.


p.s. I was looking at TimBL's old linking papers, and he called this
label-thing a "link preview," which I thought was an excellent functional
name for it.  Not to parachute in with yet another choice or anything... :-)