asterisk users - Nov 2011 - how to call a ring group via the dial plan language in asterisk?

When you are dialing a regular extension you might do something like this:

exten => Dial(123)

that would presumably dial extension 123.

but when one is using freepbx to admin the asterisk, and building a custom piece
of dial plan code, how do you access a ring group?

exten => Dial (Local/601 at xxxx)

how does one know what context to specify? and is the local keyboard needed? is
Local case sensitive?


help is appreciated.