| http://www.w3.org/ns/prov#value | - Coded magnets that have matching pseudo-random pole patterns so they lock together very strongly but only in one orientation, for instance, and other patterns that reduce the size of the field but strengthen its holding force. (This is also how rubber fridge magnets work - rub a couple of them over each other and you can easily feel the ridges" of polarisation that make the weak magnetic materi
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