ISO
8601:2000(E)
©
ISO
2000
All
rights
reserved
3
3.8
duration
quantity
("length")
of
time
3.9
format,
basic
format
of
a
representation
comprising
the
minimum
number
of
components
necessary
for
the
precision
required
3.10
format,
extended
extension
of
the
basic
format
that
includes
additional
separators
3.11
Gregorian
calendar
calendar
in
general
use;
introduced
in
1582
to
define
a
year
that
more
closely
approximated
the
tropical
year
than
the
Julian
calendar
NOTE
1
The
introduction
of
the
Gregorian
calendar
included
the
cancellation
of
the
accumulated
inaccuracies
of
the
Julian
year.
In
the
Gregorian
calendar,
a
calendar
year
is
either
a
common
year
or
a
leap
year;
each
year
is
divided
into
12
sequential
months.
NOTE
2
In
this
International
Standard
the
term
Gregorian
Calendar
is
used
to
refer
to
the
reference
system
described
in
4.3.2.1.
3.12
hour
unit
of
time
of
60
minutes,
as
defined
in
ISO
31-1
3.13
local
time
clock
time
in
public
use
locally
NOTE
The
difference
between
local
time
and
"UTC-time"
is
established
by
the
(national,
regional
or
local)
authority
responsible
for
these
matters.
The
difference
depends
upon
the
time
zone
and
may
also
be
varied
in
the
course
of
a
year.
3.14
minute
unit
of
time
of
60
seconds,
as
defined
in
ISO
31-1
3.15
month
unit
of
time
of
28,
29,
30
or
31
days
NOTE
In
certain
applications
a
month
is
regarded
as
a
unit
of
time
of
30
days.
3.16
month,
calendar
time-interval
resulting
from
the
division
of
a
calendar
year
in
12
sequential
time-intervals,
each
with
a
specific
name
and
containing
a
specified
number
of
calendar
days
NOTE
1
In
the
Gregorian
calendar,
the
months
of
the
calendar
year,
listed
in
their
order
of
occurrence,
are
named
and
contain
the
number
of
days
as
follows:
January
(31),
February
(28
in
common
years;
29
in
leap
years),
March
(31),
April
(30),
May
(31),
June
(30),
July
(31),
August
(31),
September
(30),
October
(31),
November
(30),
December
(31).
NOTE
2
A
calendar
month
is
often
also
referred
to
as
month.
3.17
period
of
time
(time-interval)
portion
of
time
between
two
time
points
NOTE
A
period
of
time
is
often
also
referred
to
as
period.
