Re: [LEAPSECS] a failure caused by lack of leap seconds

From: Ed Davies <>
Date: Sat, 09 Aug 2003 14:36:08 +0100

Steve Allen wrote:
> ...
> There are, also, uncounted documents which assert that leap seconds
> may only occur at the end of June or December. Such documents are
> provided even from organizations which ought to know that ITU-R TF.460
> permits them to occur at the end of any month.
> ...

The IERS comes within a hair's breadth of being such an organization
because IERS bulletin C can easily give this impression. While this
(from Bulletin C 26):

# Leap seconds can be introduced in UTC at the end of the months of
# December or June, depending on the evolution of UT1-TAI.

is strictly true in the sense that leap seconds can be introduced at the
ends of December or June as well as other months (it doesn't actually
say that leap seconds can *only* occur at the end of December or June)
very few people would be pedantic enough not to read it that way.

It is so misleading that it really should be fixed.

I now realise that when I commented a while ago in this list on the
wording of Bulletin C I should have drawn attention to this sentence
in combination with the one which I did quote, which was:

# NO positive leap second will be introduced at the end of December
# 2003.

Introducing a negative leap second at the end of December and
positive leap seconds at the ends of August and September, with
perhaps an extra one on November 5th just for fun, would be quite
consistent with the wording, but clearly not with the intent, of
this Bulletin.

(Yes, I know one on November 5th wouldn't be consistent with
TF.460 but it would be consistent with the Bulletin).

Ed Davies.
Received on Sat Aug 09 2003 - 06:41:30 PDT

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