> Now i have one additional case -
>  
> input:
>  
> <concept>
>       <overview>
>              <info>
>                 ...
>              </info>
>       </overview>
>       <info>
>        ...
>       </info>
> </concept>

When I first responded I said that it was very important to know the content
model before attempting to tackle this problem. It would be a good idea to
write a schema or DTD and to describe the general problem, rather than
approaching it on a case-by-case basis.

Michael Kay
http://www.saxonica.com/