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 HP 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.