OSF DCE Application Development Guide--Core Components

OSF DCE Application Development Guide—Core Components
and can convert other types of time structures to its own presentation of UTC-based time.
The DTS API routines are used to perform these conversions for applications on your
system.
Table 19-1 lists the absolute time structures that the DTS API uses to modify binary
times for applications.
TABLE 19-1. Absolute Time Structures
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Structure Time Units Base Date Approximate Range
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utc 100-nanosecond 15 October 1582 A.D. 1 to A.D. 30,000
tm second 1 January 1900 A.D. 1 to A.D. 30,000
timespec nanosecond 1 January 1970 A.D. 1970 to A.D. 2106
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Table 19-2 lists the relative time structures that the DTS API uses to modify binary times
for applications.
TABLE 19-2. Relative Time Structures
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Structure Time Units Approximate Range
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utc 100-nanosecond +/- 30,000 years
tm second +/- 30,000 years
reltimespec nanosecond +/- 68 years
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The remainder of this section explains the DTS time structures in detail.
19.2.1 The utc Structure
UTC is useful for measuring time across local time zones and for avoiding the seasonal
changes (summer time or daylight savings time) that can affect the local time. DTS uses
128-bit binary numbers to represent time values internally; throughout this guide, these
binary numbers representing time values are referred to as binary timestamps. The DTS
utc structure determines the ordering of the bits in a binary timestamp; all binary
timestamps that are based on the utc structure contain the following information:
• The count of 100-nanosecond units since 00:00:00.00, 15 October 1582 (the date of
the Gregorian reform to the Christian calendar)
• The count of 100-nanosecond units of inaccuracy applied to the preceding item
• The TDF, expressed as the signed quantity
• The DTS version number
The binary timestamps that are derived from the DTS utc structure have an opaque
format. This format is a cryptic character sequence that DTS uses and stores internally.
The opaque binary timestamp is designed for use in programs, protocols, and databases.
Note: Applications use the opaque binary timestamps when storing time values
or when passing them to DTS.
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