Extending HTML

Hi,

I'm using jTidy, and have come across a problem recently involving HTML
with non-standard extensions. I have a lot of files which contain a
certain extra tag (I suppose resulting from an error somewhere along the
production line).  Thus Tidy tells me I've got to fix this problem before
it can do the tidying. I would, however, like to leave these problem tags
intact, as they are useful in further XSL processing. Is there a way to do
this?

THanks,
Teemu