Absolute time is a point on a time scale; absolute time
    measurements are derived from system clocks or external time-
    providers. For DECdts, absolute times reference the UTC standard
    and include the inaccuracy and other information. When you
    display an absolute time, DECdts converts the time to ASCII text,
    as shown in the following display:

    1996-11-21-13:30:25.785-04:00I000.082

    Relative time is a discrete time interval that is usually added
    to or subtracted from an absolute time. A time differential
    factor (TDF) associated with an absolute time is one example
    of a relative time. Note that a relative time does not use the
    calendar date fields, because these fields concern absolute time.

    Coordinated Universal Time (UTC) is the international time
    standard that DECdts uses. The zero hour of UTC is based on
    the zero hour of Greenwich Mean Time (GMT). The documentation
    consistently refers to the time zone of the Greenwich Meridian
    as GMT. However, this time zone is also sometimes referred to as
    UTC.

    The time differential factor (TDF) is the difference between UTC
    and the time in a particular time zone.

    OpenVMS systems do not have a default time zone rule. You
    select a time zone by defining sys$timezone_rule during the
    sys$manager:net$configure.com procedure, or by explicitly
    defining sys$timezone_rule.

    The OpenVMS time structure is based on Smithsonian time,
    which has a base date of November 17, 1858. The binary OpenVMS
    structure is a signed, 64-bit integer that has a positive value
    for absolute times. You can use the DECdts API to translate an
    OpenVMS structure representing an absolute time to or from the
    DECdts UTC-based binary timestamp.

    For detailed information about DECdts time representations, refer
    to the VSI OpenVMS Utility Routines Manual.

    Unless otherwise specified, the default input and output
    parameters for the DECDts API routine commands are as follows:

    o  If utc is not specified as an input parameter, the current
       time is used.

    o  If inacc is not specified as an input parameter, infinity is
       used.

    o  If no output parameter is specified, no result (or an error)
       is returned.