| http://www.w3.org/ns/prov#value | - nner end of said double-headed key, said stem being slidable longitudinally within said rod; a replaceable supporting head including two parts coupled so that one part is capable of rotating with respect to the other and having in one of its parts a shaped opening corresponding to the shape of the cross section of said threaded end of the stem, and a central threaded opening in its other part whic
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