my next file to study com.apple.wifi.plist (firmware 2.1)
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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>AllowEnable</key>
<integer>1</integer>
<key>Custom network settings</key>
<dict/>
<key>JoinMode</key>
<string>Automatic</string>
<key>List of known networks</key>
<array>
<dict>
<key>AGE</key>
<integer>354</integer>
<key>AP_MODE</key>
<integer>1</integer>
<key>AuthPasswordEncryption</key>
<string>SystemKeychain</string>
<key>BEACON_INT</key>
<integer>10</integer>
<key>BSSID</key>
<string>2:1c:bf:1:93:56</string>
<key>CAPABILITIES</key>
<integer>50</integer>
<key>CHANNEL</key>
<integer>11</integer>
<key>CHANNEL_FLAGS</key>
<integer>8</integer>
<key>HIDDEN_NETWORK</key>
<false/>
<key>NOISE</key>
<integer>0</integer>
<key>RATES</key>
<array>
<integer>1</integer>
<integer>2</integer>
<integer>5</integer>
<integer>11</integer>
<integer>6</integer>
<integer>9</integer>
<integer>12</integer>
<integer>18</integer>
<integer>24</integer>
<integer>36</integer>
<integer>48</integer>
<integer>54</integer>
</array>
<key>RSSI</key>
<integer>57</integer>
<key>SSID</key>
<data>
aG90c3BvdA==
</data>
<key>SSID_STR</key>
<string>hotspot</string>
<key>WEP</key>
<true/>
<key>WEPKeyLen</key>
<integer>5</integer>
<key>WEPType</key>
<integer>0</integer>
<key>authMode</key>
<integer>4</integer>
<key>isValid</key>
<true/>
<key>isWPA</key>
<integer>0</integer>
<key>lastJoined</key>
<date>2008-12-30T13:45:26Z</date>
<key>scanWasDirected</key>
<false/>
</dict>
</array>
</dict>
</plist>