The OpenVMS Greenwich Mean Time routine converts a UTC-based
    binary timestamp to a 64-bit binary time in the OpenVMS
    (Smithsonian) format. The OpenVMS format time represents
    Greenwich Mean Time or the equivalent UTC. Because the input and
    output values are based on different time standards, any input
    representing a value before the Smithsonian base time of November
    17, 1858 returns an error.