OSF DCE Administration Guide--Core Components

Introduction to DCE Distributed Time Service
Although the dcecp clock show command displays all times in the previous format (see
Figure 23-4), the interface also accepts the following variations to the ISO format on
input, as shown in Figure 23-5.
Figure 23-5. ISO-Compliant Time Format Variation
CCYY−MM−DDThh:mm:ss,fff[+|−]hh:mm
ss,fff
+
−
Inaccuracy
component
TDF
component
Calendar date and time
component
fractions
seconds
Inaccuracy
designator
minutes
hours
+| − TDF
Century
Year
Month
Day
Time
designator
hour
minute
second
fraction
In the preceding example, the delineator T separates the calendar date from the time, a ,
(comma) separates seconds from fractional seconds, and the ± (plus-or-minus sign)
indicates the beginning of the inaccuracy component.
DTS offers a translation feature that changes UTC-based absolute times to your local
time whenever the time is displayed. The local time displayed is derived from UTC plus
a Time Differential Factor (TDF), which can have a positive or negative value. In the
previous example, the string [+/-] hh :mm denotes the TDF. When installing a system,
you select a time-zone rule for the system, which determines the TDF and any seasonal
changes to the TDF. After the initial startup, all subsequent output times reflect the local
time. If an absolute time is displayed by your system, and it does not contain TDF
information, it is a UTC time.
The following section describes relative time, which is derived from absolute time.
23.2.5.2 Relative Time
A relative time is a discrete time interval that is usually added to or subtracted from
another time. The TDF that is associated with absolute times is an example of a relative
time. Relative times are normally used as input for commands or system routines.
Figure 23-6 shows the format for relative time.
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