[XHTML 2] 17 Embedding Attributes

Dear HTML Working Group,

Please provide some informative text explaining the motivation for embedding 
attributes, I can see no obvious use cases or benefits in the section, The 
first example is

<p src="holiday.png" srctype="image/png">
    <span src="holiday.gif" srctype="image/gif">
        An image of us on holiday.
    </span>
</p>

I do not understand the example, somehow there is an image somewhere which 
has the same semantics as the text "An image of us on holiday", whilst I'm 
very poor in understanding images, the only realistic image I could imagine 
for this is the text "An image of us on holiday"  Seen as I can see little 
or no reason as to why an author would want to do this, please add some 
clarification, also explain why it's superior to the alternative of:

<p>
<img src="holiday" srctype="image/png, image/gif;q=0.5">
An image of us on holiday
</img>
</p>

(Or the same without content negotiation for the image, with two img 
elements)

I regard this as containing more semantic information than the previous 
example, since it specifically contains the information that the src is an 
image, and not some other type of content.  Please add information to the 
specification as to why it's better.  Or if it's not please remove the 
embedding attributes model from XHTML 2.0.

The 2nd example is equivalent to:

<img src="temperature-graph.png" srctype="image/png">
<table>
<caption>Average monthly temperature over the last 20 years</caption>
<tr><th>Jan</th><th>Feb</th><th>Mar</th><th>Apr</th><th>May</th><th>Jun</th>
    <th>Jul</th><th>Aug</th><th>Sep</th><th>Oct</th><th>Nov</th><th>Dec</th>
</tr>
<tr><td> 4</td><td> 2</td><td> 7</td><td> 9</td><td>13</td><td>16</td>
    <td>17</td><td>17</td><td>14</td><td>11</td><td> 7</td><td> 4</td>
</tr>
</table>
</img>

Again the fact that temperature-graph.png is an image is useful semantic 
information that is lost in the example in the specification.  Also it is 
not clear how an image can be equivalent to a table, it's possible they 
contain the same information, but that does not make an image a table.

Some more complicated situations that also need explaining, what is the 
utility in being able to do

<p src="text.css" srctype="text/css">
The cat sat on the mat.
</p>

or

<xhtml ...>
<head>
<style src="text.xhtml" srctype="application/xhtml+xml; version=2; 
text/css;q=0.5">
#head { display:block }
</style>
</head>

What should happen in this situation, when text.xhtml is successful as an 
XHTML document, as a CSS document, or a failure?

Please clarify the motivation for the whole Embedding attributes section, 
and remove any ambiguity in the various situations above.  I currently 
regard the entire section to be under defined and to contain no valid use 
cases.  Alternatively please remove section 17.

Regards,

Jim Ley

Received on Sunday, 29 May 2005 14:00:23 UTC