Here's my config...
interface wireless> print
Flags: X - disabled, R - running
0 R name="Wlan" mtu=1500 mac-address=00:02:6F:xx:xx:xx arp=enabled disable-running-check=no interface-type=Prism
prism-cardtype=200mW radio-name="00026F365B9C" mode=ap-bridge ssid="wlanap" area="" frequency-mode=superchannel
country=no_country_set antenna-gain=0 frequency=2437 band=2.4ghz-b scan-list=default rate-set=default
supported-rates-b=1Mbps,2Mbps,5.5Mbps,11Mbps basic-rates-b=1Mbps max-station-count=2007 tx-power-mode=default
periodic-calibration=default dfs-mode=none antenna-mode=ant-a wds-mode=disabled wds-default-bridge=none
wds-ignore-ssid=no update-stats-interval=disabled default-authentication=no default-forwarding=yes
default-ap-tx-limit=0 default-client-tx-limit=0 hide-ssid=no security-profile=default disconnect-timeout=3s
on-fail-retry-time=100ms preamble-mode=long compression=no allow-sharedkey=no
1 R name="Wlan2" mtu=1500 mac-address=00:02:6F:xx:xx:xx arp=enabled disable-running-check=no interface-type=Prism
prism-cardtype=200mW radio-name="00026F39F5F9" mode=ap-bridge ssid="wlanap2" area="" frequency-mode=superchannel
country=no_country_set antenna-gain=0 frequency=2457 band=2.4ghz-b scan-list=default rate-set=default
supported-rates-b=1Mbps,2Mbps,5.5Mbps,11Mbps basic-rates-b=1Mbps,2Mbps,5.5Mbps,11Mbps max-station-count=2007
tx-power-mode=default periodic-calibration=default dfs-mode=none antenna-mode=ant-a wds-mode=disabled
wds-default-bridge=none wds-ignore-ssid=no update-stats-interval=disabled default-authentication=yes
default-forwarding=yes default-ap-tx-limit=0 default-client-tx-limit=0 hide-ssid=no security-profile=default
disconnect-timeout=3s on-fail-retry-time=100ms preamble-mode=long compression=no allow-sharedkey=no
2 R name="wlan1" mtu=1500 mac-address=00:02:6F:xx:xx:xx arp=enabled disable-running-check=no interface-type=Prism
prism-cardtype=200mW radio-name="00026F3691E4" mode=ap-bridge ssid="wlanap1" area="" frequency-mode=superchannel
country=no_country_set antenna-gain=0 frequency=2412 band=2.4ghz-b scan-list=default rate-set=default
supported-rates-b=1Mbps,2Mbps,5.5Mbps,11Mbps basic-rates-b=1Mbps,2Mbps,5.5Mbps,11Mbps max-station-count=2007
tx-power-mode=default periodic-calibration=default dfs-mode=none antenna-mode=ant-a wds-mode=disabled
wds-default-bridge=none wds-ignore-ssid=no update-stats-interval=disabled default-authentication=no
default-forwarding=yes default-ap-tx-limit=0 default-client-tx-limit=0 hide-ssid=no security-profile=default
disconnect-timeout=3s on-fail-retry-time=100ms preamble-mode=long compression=no allow-sharedkey=no