Read metadata_charset.txt in Firebird's misc\upgrade\metadata directory. It may help you.

--- In firebird-support@yahoogroups.com, "Ian A. Newby" <ian@...> wrote:
>
> Hi folks,
> I've been happily using character set none since firebird 0.9 beta and my live system is currently running on firebird 1.5.x.
>
> I am in the process of test migrating the system from 1.5.x to 2.1.x and have noticed a strange issue.
>
> The application is a tomcat web app which servers pages built from pages stored in the database. With 1.5, apostrophe (') in the database are shown as expected. With 2.1, they appear as a ? character (unknown).
>
> My gut feel is that this is to do with the new unicode support introduced in fb2.
>
> So the question is, should I bite the bullet and migrate to a different character set, and if so, which one? (The system is used in the UK).
> Would this correct my apostrophe issue or would I need to find them all in the database and correct them manually.
>
> Regards
> Ian Newby
>