1.anyinstructionthatworksfirstone wayand thenthe other
2.ahingedswitchthatcanassumeeitheroftwopositions
3.afastenerconsistingofapegorpinorcrosspiecethat isinsertedintoaneyeat the end ofaropeorachainoracablein order tofastenittosomething (asanotherropeorchainorcable)