| http://www.w3.org/ns/prov#value | - An erasing system including a marking board having a smooth, hard, non-porous surface of plastic and a porous point pen having an ink therein which will deposit uniform, legible traces, markings or lines on said plastic surface and which can be removed therefrom with a dry cloth or paper tissue. 15 Claims, No Drawings MARKING BOARDS AND ERAS'ABLE INK COMPOSITIONS THEREFOR BACKGROUND OF THE INVENTI
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