<s>
In	O
music	O
a	O
time	B-Algorithm
point	I-Algorithm
or	O
timepoint	O
(	O
point	O
in	O
time	O
)	O
is	O
"	O
an	O
instant	O
,	O
analogous	O
to	O
a	O
geometrical	O
point	O
in	O
space	O
"	O
.	O
</s>
<s>
Milton	O
Babbitt	O
calls	O
the	O
distance	O
from	O
one	O
time	B-Algorithm
point	I-Algorithm
,	O
attack	O
,	O
or	O
starting	O
point	O
to	O
the	O
next	O
a	O
time-point	B-Algorithm
interval	O
,	O
independent	O
of	O
the	O
durations	O
of	O
the	O
sounding	O
notes	O
which	O
may	O
be	O
either	O
shorter	O
than	O
the	O
time-point	B-Algorithm
interval	O
(	O
resulting	O
in	O
a	O
silence	O
before	O
the	O
next	O
time	B-Algorithm
point	I-Algorithm
)	O
,	O
or	O
longer	O
(	O
resulting	O
in	O
overlapping	O
notes	O
)	O
.	O
</s>
<s>
The	O
corresponding	O
term	O
used	O
in	O
acoustics	O
and	O
audio	O
engineering	O
to	O
describe	O
the	O
initiation	O
of	O
a	O
sound	O
is	O
onset	B-Application
,	O
and	O
the	O
interonset	O
interval	O
or	O
IOI	O
is	O
the	O
time	O
between	O
the	O
beginnings	O
or	O
attack	O
points	O
of	O
successive	O
events	O
or	O
notes	O
,	O
the	O
interval	O
between	O
onsets	O
,	O
not	O
including	O
the	O
duration	O
of	O
the	O
events	O
.	O
</s>
<s>
A	O
variant	O
of	O
this	O
term	O
is	O
interval	O
of	O
onset	B-Application
.	O
</s>
<s>
In	O
serial	O
music	O
a	O
time-point	B-Algorithm
set	I-Algorithm
,	O
proposed	O
in	O
1962	O
by	O
Milton	O
Babbitt	O
,	O
is	O
a	O
temporal	O
order	O
of	O
pitches	O
in	O
a	O
tone	O
row	O
which	O
indicates	O
the	O
instants	O
at	O
which	O
the	O
notes	O
start	O
.	O
</s>
<s>
This	O
has	O
certain	O
advantages	O
over	O
a	O
duration	B-Algorithm
scale	I-Algorithm
or	O
row	O
built	O
from	O
multiples	O
of	O
a	O
unit	O
,	O
derived	O
from	O
Olivier	O
Messiaen	O
.	O
</s>
<s>
The	O
start	O
of	O
each	O
position	O
,	O
or	O
time	B-Algorithm
point	I-Algorithm
,	O
may	O
then	O
be	O
labeled	O
,	O
in	O
order	O
,	O
0	O
–	O
11	O
.	O
</s>
<s>
In	O
Babbitt	O
's	O
first	O
example	O
he	O
shows	O
subsequent	O
numbers	O
which	O
ascend	O
(	O
0	O
–	O
11	O
)	O
as	O
within	O
the	O
same	O
measure	O
(	O
if	O
four	O
follows	O
three	O
it	O
may	O
sound	O
immediately	O
)	O
,	O
and	O
subsequent	O
numbers	O
which	O
descend	O
as	O
in	O
the	O
following	O
measure	O
(	O
if	O
three	O
follows	O
four	O
it	O
must	O
necessarily	O
wait	O
for	O
the	O
next	O
appearance	O
of	O
time-point	B-Algorithm
three	O
)	O
.	O
</s>
<s>
Babbitt	O
uses	O
time	B-Algorithm
points	I-Algorithm
in	O
Partitions	O
(	O
1957	O
)	O
,	O
All	O
Set	O
(	O
1957	O
)	O
,	O
and	O
Post-Partitions	O
(	O
1966	O
)	O
,	O
as	O
well	O
as	O
in	O
Phonemena	O
(	O
1969	O
–	O
70	O
)	O
,	O
String	O
Quartets	O
No	O
.	O
</s>
<s>
Charles	O
Wuorinen	O
has	O
also	O
developed	O
an	O
approach	O
to	O
the	O
time-point	B-Algorithm
system	O
,	O
which	O
differs	O
greatly	O
from	O
Babbitt	O
's	O
.	O
</s>
