[LEAPSECS] LEAPSECS Digest, Vol 51, Issue 8

[Tony Finch]

On Wed, 2 Feb 2011, Finkleman, Dave wrote:

>

> With regard to terminology, there are at least three "normative"

> definitions of the second among ISO standards.  8601, Data Exchange

> Formats, sanctions everything under the Sun.  Maybe everything in the

> Universe.


My copy of the 2004 edition says:

	2.2 Time units, nominal durations and time intervals

	2.2.1 second

	base unit of measurement of time in the International System of
	Units (SI) as defined by the International Committee of Weights
	and Measures (CIPM, i.e. Comité International des Poids et
	Mesures)

	NOTE 1 See also ISO 31-1.
	NOTE 2 It is the base unit for expressing duration.

I can't immediately find any caveats or hedges around this definition.

One oddity is that 8601:2004 defines "minute", "day", and "hour" in a way
that does not allow for leap seconds, whereas "calendar day" allows for
leap seconds and timezone (DST) adjustments.

The 1988 edition is a lot more crazy in the variety of formats it
defines, but its definition of the second is basically equivalent.

	3 Terms and definitions

	3.14 second: A basic unit of measurement of time in the

Tony.
-- 
f.anthony.n.finch  <dot at dotat.at>  http://dotat.at/
HUMBER THAMES DOVER WIGHT PORTLAND: NORTH BACKING WEST OR NORTHWEST, 5 TO 7,
DECREASING 4 OR 5, OCCASIONALLY 6 LATER IN HUMBER AND THAMES. MODERATE OR
ROUGH. RAIN THEN FAIR. GOOD.