can i use flags at once?

[Giorgos Tsiapaliokas]

hello,

i am a gentoo user and now i am trying to install a freebsd on my machine.
ports are great but while my machine is compiling i receive messages about
the flags.

in gentoo i was able via the file /etc/portage/package.use to determine
which flags i wanted to enable and which not.

is there any way to do this in FreeBSD,since gentoo's portage is based on
ports.

thanks in advance.