custom exception number range && jdbc?

hi there, i'm using jdbc && informix spl for a stand alone java app. in the spl, i'm raising custom exceptions and catching normal exceptions to pass back more user friendly messages. i have a table where i keep my custom exception messages and numbers. it does seem to work for certain exception numbers, but not others -- is there ranges that are already marked off? i've looked at the error message list, and tried using ranges that are free, but for some of the ranges it seems to be looking for error messages in other files (e.g. perf.iem) rather than the one specified in the 'raise exception num, 0, message' (which is how i'm raising my custom exception). so... does anyone know the acceptable ranges for custom exceptions? thanks in advance! ///daly