A time-differential analog comparator is disclosed. The working surface andor the components can have machine-readable codes to assist the agents in maintaining current knowledge of their respective locations. G\u2032, G\u2032G\u2032 is from 1\xd7102 to 1\xd7104; a ratio of a storage modulus at 100\xb0 C. As the different copies can be stored in different locations, it is unlikely that a cosmic ray impact would affect all copies equally.