Hi, I think I stumbled on a GenBank oriented parser (especially, quite useful when you are reading a gene sequence) while reading Perl for Bioinformatics. I`ll check it out, and let you know. Nevertheless, I would like to learn how to use flags to mark the beginning and end of a block to be processed. That is, for the example in this thread, I want the code to make the adequate matchings only when encountered a CDS block (which starts with \s*CDS and ends with \s*gene) but not a mRNA block. Well, I still did not manage to, though. I understood how it works but could not figure out how to implement. :)