On Wed, Mar 14, 2012 at 12:58 PM, Alan Watson <[email protected]> wrote: > After an illuminating discussion with Steve Allen, I have two further remarks. > > Steve points out that the predecessor of TAI was not called TAI in 1970. > Therefore, it might be better to say that current-second returns "The number > of seconds elapsed since 1970-01-01 00:00:00 as measured in the atomic time > scale then maintained by the BIH. This time scale was later renamed TAI, and > it has been maintained by the BIPM since 1988." (Alternatively, you might use > the words from IEEE 1588-2008, but I'm not going to plunk down 180 bucks just > to find out what they say.) > > Steve also reminds us there is some doubt as to the long-term existence of > TAI. The CCTF has stated[1]: "In the case of a redefinition of UTC without > leap seconds, the CCTF would consider discussing the possibility of > suppressing TAI, as it would remain parallel to the continuous UTC."
We use "TAI" for lack of a better term. What the draft current-seconds does is return a monotonic time - an unmolested number of seconds since an epoch. Your formal comment suggests changing that epoch, not the definition of a second. The continued existence of "number of seconds" is not in any danger. Converting to TAI or UTC calendar time is a matter for WG2, and we will likely want to provide both of these, as well as Julian time and other historic calendars for completeness, even should they become obsolete. > This suggests that it might be wiser to define current-second to return the > number of UTC seconds since an arbitrary epoch and provide a means to convert > this to and from UTC calendar dates (either explicitly or by exposing the > epoch). The number of UTC seconds is the same as the number of TAI seconds. -- Alex _______________________________________________ Scheme-reports mailing list [email protected] http://lists.scheme-reports.org/cgi-bin/mailman/listinfo/scheme-reports
