It would be helpful to allow the revnumber to be automatically included in the name of the output file. This saves the user from having to remember to use the -o flag to specify a file name and align it with the revnumber.
If there's an easy way to do this without built-in support, then we should simply document it.
We'll need an option or attribute for this. I think an option makes the most sense since this is really something that is controlled at the level of the -o flag. Perhaps --version-out-file?