norman.walsh.name: Comments on /2006/01/17/xmlLanguages http://norman.walsh.name/2006/01/17/xmlLanguages/comments.atom 2006-01-18T21:13:47Z Comment 1 on /2006/01/17/xmlLanguages http://norman.walsh.name/2006/01/17/xmlLanguages#comment0001 2006-01-17T17:24:01Z 2006-01-17T17:24:01Z Elliotte Rusty Harold fcc9a2c3412d8d046a24619e3aa59dadeec7dc91 http://cafe.elharo.com/
Norm, all three of the options you present are suboptimal. HTML must-ignore enables us to do this: 
<p>The Eiffel Tower is located at
 <geo xmlns="http://example.org/geo">
  <latitude>48.8589</latitude>° latitude 
  <longitude>2.2958</longitude>° longitude
</geo>.
</p>
This will display correctly in essentially all existing browsers, no stylesheet required. I've been using markup like this for years on Cafe con Leche and Cafe au Lait. It works. It doesn't cause any problems. It's easy to validate. It's easy to process. Just don't stuff content you want humans to read in attribute values and you'll be fine.
 Comment 2 on /2006/01/17/xmlLanguages http://norman.walsh.name/2006/01/17/xmlLanguages#comment0002 2006-01-17T17:34:17Z 2006-01-17T17:34:17Z Norman Walsh 9f5c771a25733700b2f96af4f8e6f35c9b0ad327 http://norman.walsh.name/

Yes, Elliotte, you're right. I chose the example to illustrate a problem, but I should equally have illustrated the workaround. In fact, I had initially done what you suggest, but changed it to highlight the point I wanted to make about must ignore.

 Comment 3 on /2006/01/17/xmlLanguages http://norman.walsh.name/2006/01/17/xmlLanguages#comment0003 2006-01-17T18:55:17Z 2006-01-17T18:55:17Z Steve Loughran 80f5e544ad8be8358acc31ca6ec24c5a20bb1291 http://www.1060.org/blogxter/publish/5
The problem of what to do with unknown tags has existed since HTTP0.9. The early NeXT HTTP browser ignored unknown stuff, with consequences that were noted way back in 1993: http://catless.ncl.ac.uk/Risks/14.75.html#subj2.1

It was probably incidents like these that led to the current policy, one that caused problems the moment the script tag was added, hence most javascript element bodies hide the content in a comment, to stop the script ignorant browsers from displaying it.

It really does need improving. Maybe an attribute that set the notunderstood to either "skip" or "display". I don't approve of "fail" on unknown tags, as it would make too much stuff unreadable by odd browsers.

Comment 4 on /2006/01/17/xmlLanguages http://norman.walsh.name/2006/01/17/xmlLanguages#comment0004 2006-01-18T16:46:49Z 2006-01-18T16:46:49Z Elliotte Rusty Harold fcc9a2c3412d8d046a24619e3aa59dadeec7dc91 http://cafe.elharo.com/

The script element is the flip side of what I was complaining about in Norm's examples. The script should have been placed in an attribute value because it's not intended for human readers. Then the problems wouldn't have arisen. Java got this right. It's surprising JavaScript didn't.

Here's the rule: if you want people to read the text make it element content. If you want them not to see it, put it in an attribute value.

MustIgnore, MustUnderstand, and so forth are fundamentally bad ideas. The author of the document does not get to tell the reader what they do or do not or must or must not understand. The author does not get to specify what processing the reader does. Authorial intent is bogus and irrelevant.

 Comment 5 on /2006/01/17/xmlLanguages http://norman.walsh.name/2006/01/17/xmlLanguages#comment0005 2006-01-18T21:13:47Z 2006-01-18T21:13:47Z Norbert Lindenberg 286c07e6c6ca6a920c49799d23da309b084af07e

Elliotte, your solution works fine if both human readers and software are happy with the same representation of the data. But what if you want to show today’s date to your human readers as 平成18年1月18日, while feeding 2006-01-18 to software?