KML is very extensible ... but why?

["Costello, Roger L." <costello@mitre.org>]

Hi Folks,

 

The format of KML 2.3 documents are specified with a W3C 1.1 XML Schema. XML Schema 1.1 has a powerful feature which KML uses. At the top of the KML schema is this:

  <defaultOpenContent mode="interleave">
      <any namespace="##other" processContents="lax"/>
   </defaultOpenContent>

Read as: "KML documents are open. That is, XML elements from any non-KML namespace can be inserted before and after every element in KML documents. Those non-KML elements do not have to validate against any schema."

 

That makes KML very extensible.

 

But why?

 

If I add non-KML stuff in a KML instance, who’s going to understand my stuff? Google Earth? No. Google Maps? No. NASA WorldWind? No.

 

Only applications that have been custom-coded to understand my stuff will be able to do anything with it. Right? Doesn’t that destroy KML as a global geographic annotation/visualization language since now you’ve got all these non-interoperable dialects floating around?

 

Thoughts?

 

/Roger