{HEAD ~ Still another object} of the invention is to provide a focus transparency which can be stored in a protector and whose image is that of a test pattern useable in conjunction with a registration device for centering and focusing of {TAIL ~ the overhead optical projector} before beginning a presentation of visual aid transparencies 
{ HEAD ~ Still another object } of the invention is to provide a focus transparency which can be stored in a protector and whose image is that of a test pattern useable in conjunction with a registration device for centering and focusing of { TAIL ~ the overhead optical projector } before beginning a presentation of visual aid transparencies
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