Ni-based Cr- and P-bearing alloys that can from centimeter-thick amorphous articles are provided. The methods include accessing the primary optical fiber of the legacy 850 nm optical-fiber link and optically connecting thereto one or more sections of compensating optical fiber. An alternative guide arm has more than one attachment site for removably affixing a sensor holder to the guide arm. A first representation of a first pattern and a second representation of the first pattern can be encoded on the magnetic stripe.