interfaces - Connect to unencrypted network in raspbian

Question

I want to connect to a network that has no encryption on it. I have the below to connect to an encrypted network but I can't find how to connect to an unencrypted network.

How do I specify the ssid etc to connect to an unencrypted network?

/etc/network/interfaces

auto wlan0
iface wlan0 inet dhcp
   wpa-driver wext
   wpa-ssid "myssid"
   wpa-ap-scan 1
   wpa-proto RSN
   wpa-pairwise CCMP
   wpa-group CCMP
   wpa-key-mgmt WPA-PSK
   wpa-psk "mypass"

Answer 1

It is an open network so there is no key management, grouping or password and it is simply:

network={
        ssid="starbucks"
        key_mgmt=NONE
}