As stated above, the Master and User Devices 220, 222, 224 may be any number of electronic devices including, but not limited to, PDAs, {HEAD ~ mobile telephones}, {TAIL ~ mobile PCs} or desktop units, televisions, amulets, or other pure input/output devices 
As stated above , the Master and User Devices 220 , 222 , 224 may be any number of electronic devices including , but not limited to , PDAs , { HEAD ~ mobile telephones } , { TAIL ~ mobile PCs } or desktop units , televisions , amulets , or other pure input / output devices
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