On 2014-01-19 11:06 AM, Joseph Gwinn wrote:
NTP *does* refer to POSIX - Figure 4: Interesting Historic NTP Dates refers to "First day UNIX" and locates it 63072000 seconds before 1972-01-01T00:00:00Z (UTC). This helps solve one problem - when, exactly, was the POSIX "the Epoch". Ok. I meant a normative reference, in the sense of coordinated standards. An interesting historical note isn't really coordination.
Its debatable if "Figure 4: Interesting Historic NTP Dates" is normative or informative. Nothing says its informative, so, except for the word "Interesting" in its title, it could be considered normative.
Its the closet thing I know of that definitively places the Unix/POSIX "the Epoch" in relation to 1972-01-01T00:00:00Z (UTC).
In any event it must describe the common use of many systems that synchronize NTP with POSIX.
The intentional fuzzy definition of POSIX "the Epoch" is a major gap in the fractured time-keeping standards, a gap that is probably responsible for a lot of misunderstanding and non-interoperable implementations.
This is a key objective of the CCT design I've suggested - to *specify* the relationship of the origin called "ACCT1970" as 63072000 seconds before 1972-01-01T00:00:00Z (UTC), or 1972-01-01T00:00:00Z (CCT).
This is exactly the same as NTP's reference to "First day Unix", and the best choice for accurate date-time implementations in POSIX.
The "ACCT1970" origin is named to separate it from any direct normative dependencies on the NTP or POSIX standards, insulating it from debates in those arenas. But it would informatively state "ACCT1970 in intended to coincide with the Unix/POSIX "the Epoch" and applications may choose to treat it so."
-Brooks
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