Peter Eisentraut <peter_e(at)gmx(dot)net> writes:
> Perhaps I might have been less confused if meaning (b) used a different
> character, say "username!".
Well, maybe ... but do we want to create two special characters in
usernames, instead of one? @ still has to be considered special in
incoming usernames, else you have no security against local users
connecting to other databases.
regards, tom lane