Thanks to all for your comments.... It's a pity this class of functionality is not implemented in boost. I'm in the bioinformatics field and starting to work with boost. The use of regex in general as boost implements is quite common in the field and boost is very handy.!!! However at some point some advanced functionalities with insertion,deltions and repeats are very handy to use. Maybe there's a chance that some of the work out there get into boost as a boost_bio module ??? Note that biocpp.sourceforge.net has done some work on bioinformatics and that maybe it would be interesting to know if they were willing to move their codeinto boost. This will avoid people from having to install thousands of libraries to do their work. What do you think ??