please explain these gpg switches...

[seberino@xxxxxxxxxxxxxxx]

Here is .muttrc line to sign emails:

set pgp_sign_command="gpg --no-verbose --batch --quiet --output -
--passphrase-fd 0 --armor --detach-sign --textmode %?a?-u %a? %f"

I'm confused about some switches in .muttrc line above:

--no-verbose  : Why do we need this to "reset the verbosity level"??
                 ... why isn't `--quiet' good enough??

--armor       : What does this too? Add a checksum only?
                man pages still left me confused

--detach-sign : this "detaches" the signature.  what does that mean?

--textmode %?a?-u %a? %f  I'm most confused about all this cruft and
                          what all these question marks and %f means.

Any help would be greatly appreciated.

Sincerely,

Chris