How to drop empty attributes?

Hi,

I use tidy to get valid xhtml code out of a web content management 
system. Everything works great but I have one last Problem. Due to some 
reasons the system I use generates links in the following format:

<a href="http://www.test.com/index.htm" target="">A link</a>

If you don't specify a target the target attribute will be empty as 
shown above. My question is, how to tell tidy to remove such empty 
attributes, since they are not valid xhtml 1.0 transitional.


Thanks in advance,

best regards, René