Eric is correct, your designation as a fortran maintainer is a step
above and subsumes plain "write-after-approval". Maintainers of
particular parts of GCC have implicit "write-after-approval"
everywhere else outside their domain. So once someone who has checkin
authority over the parts you touch approves a patch you can check it
in.
The policy is formalized under the "Localized write permission" here:
http://gcc.gnu.org/svnwrite.html
If you feel the language is ambiguous, please feel free to suggest
something better.