What files modified by --quick-set-expire ? (pls CC me)

[Douglas Lucas]

Dear gnupg-users,

When I invoke "$ gpg2 --quick-set-expire" to modify a public key, a sub
key, or a secret key, what file(s) are modified by gpg2? In other words,
by default, what are the public/sub/secret key files that are changed
once a quick extension is invoked?

Please CC me on your answers as I'm not subscribed to the list.

Thanks much,

Douglas