{HEAD ~ The present invention} relates generally to {TAIL ~ devices} for interacting with computer systems, and in particular, to a device which may be used to render otherwise passive surfaces audiovisually interactive via invisible surface codings 
{ HEAD ~ The present invention } relates generally to { TAIL ~ devices } for interacting with computer systems , and in particular , to a device which may be used to render otherwise passive surfaces audiovisually interactive via invisible surface codings
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