Thank you so much for all your help. I am all set now.
I appreciate everybody's input in helping me to understand this complicated part of Perl Regular expression. :)
Please let me know how can i close this topic?
We don't explicitly close topics on this forum: standard protocol is including a message like this parent telling everyone that the issue is resolved. If the solution is inobvious, it's also considered good form to include your solution and code. Of course, this usually invites code commentary, so consider it optional.