Abstract: A uniformly distributed magnetic recording medium is carried on or in an initially fluidizable support. During or after magnetically writing information upon the medium, the support is changed to a fluidized state, sufficient to permit some physical translational movement of the medium in localized areas corresponding in pattern to characteristic magnetic non-uniformities caused in medium by the magnetic writing. The support is then set or otherwise converted to a state in which such movement is no longer possible. Thereafter, even if the medium is degaussed, the now set non-uniformities in physical distribution of the recording medium, will permit the information that had been magnetically written, to continue to be read e.g. by magnetic analysis of the medium.

Abstract: Sidewalls of cans from one filling and closing line are magnetized to provide each with a north pole oriented toward the can top. Sidewalls of cans from another filling and closing line are magnetized to provide each with a south pole oriented toward the can top. These tagged cans are randomly merged into one line for further processing without mixing up can top orientations, for instance, for cooking in a conveyor-fed continuous cooker in order to keep the cooker operating nearer full capacity. Then, each can passes a magnetic sensing station where one (top) end of each can is investigated by a probe which senses whether that end is a north pole or a south pole. The sensing station commands a diverter downstream which shunts the cans sensed as having north pole ends into a different line from the cans sensed as having south pole ends.