Hi Shawn, Thanks for the detailed explanations.
But Edward(see one of posts in my thread) tells me to try Bio::SeqIO from www.bioperl.org. After I try I think it is what I really need. Once again thank you so much for the help. Li __________________________________________ Yahoo! DSL Something to write home about. Just $16.99/mo. or less. dsl.yahoo.com -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] <http://learn.perl.org/> <http://learn.perl.org/first-response>