[xml] Properties (attributes) with no value.

["Adam Jerome" <AJEROME novell com>]

xmlGurus,

I am a very pleased "new user" of libxml.  
To all those who have been involved with the development of this
library:  "Well Done!"

A question....

Do XML standards require (and/or does libxml require) that properties
(ie :attributes) always have an associated value?   

Considering the following example:

   <ELEMENT attribute="true">

Would the following be within XML standards:?
  
   <ELEMENT attribute>

Such might be useful as a (shorthand) boolean flag using xmlHasProp(). 
If the attribute exists, then [attribute="true"] can be assumed;
otherwise, [attribute="false"] can be assumed.

If this methodology is sound, I would like to implement such
methodology in my application.  I have attempted to do so with:

   xmlSetProp(..., "attribute", NULL);

However, this resulted in:

   <ELEMENT attribute="">

... when I was hoping to generate:

   <ELEMENT attribute>

Is there a way to do this, or is my methodology "out in the weeds"?

-adam