<s>
Dot-decimal	B-Protocol
notation	I-Protocol
is	O
a	O
presentation	O
format	O
for	O
numerical	O
data	O
.	O
</s>
<s>
It	O
consists	O
of	O
a	O
string	O
of	O
decimal	B-Application
numbers	O
,	O
using	O
the	O
full	O
stop	O
(	O
dot	O
)	O
as	O
a	O
separation	O
character	O
.	O
</s>
<s>
A	O
common	O
use	O
of	O
dot-decimal	B-Protocol
notation	I-Protocol
is	O
in	O
information	O
technology	O
where	O
it	O
is	O
a	O
method	O
of	O
writing	O
numbers	O
in	O
octet-grouped	O
base-10	O
(	O
decimal	B-Application
)	O
numbers	O
.	O
</s>
<s>
In	O
computer	B-Architecture
networking	I-Architecture
,	O
Internet	O
Protocol	O
Version	O
4	O
(	O
IPv4	O
)	O
addresses	O
are	O
commonly	O
written	O
using	O
the	O
quad-dotted	B-Protocol
notation	I-Protocol
of	O
four	O
decimal	B-Application
integers	O
,	O
ranging	O
from	O
0	O
to	O
255	O
each	O
.	O
</s>
<s>
In	O
computer	B-Architecture
networking	I-Architecture
,	O
the	O
notation	O
is	O
associated	O
with	O
the	O
specific	O
use	O
of	O
quad-dotted	B-Protocol
notation	I-Protocol
to	O
represent	O
IPv4	O
addresses	O
and	O
used	O
as	O
a	O
synonym	O
for	O
dotted-quad	O
notation	O
.	O
</s>
<s>
Dot-decimal	B-Protocol
notation	I-Protocol
is	O
a	O
presentation	O
format	O
for	O
numerical	O
data	O
expressed	O
as	O
a	O
string	O
of	O
decimal	B-Application
numbers	O
each	O
separated	O
by	O
a	O
full	O
stop	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
hexadecimal	O
number	O
0xFF000000	O
may	O
be	O
expressed	O
in	O
dot-decimal	B-Protocol
notation	I-Protocol
as	O
255.0.0.0	O
.	O
</s>
<s>
An	O
IPv4	B-Protocol
address	I-Protocol
has	O
32	O
bits	O
.	O
</s>
<s>
For	O
purposes	O
of	O
representation	O
,	O
the	O
bits	O
may	O
be	O
divided	O
into	O
four	O
octets	O
written	O
in	O
decimal	B-Application
numbers	O
,	O
ranging	O
from	O
0	O
to	O
255	O
,	O
concatenated	O
as	O
a	O
character	O
string	O
with	O
full	O
stop	O
delimiters	O
between	O
each	O
number	O
.	O
</s>
<s>
This	O
octet-grouped	O
dotted-decimal	B-Protocol
format	O
may	O
more	O
specifically	O
be	O
called	O
"	O
dotted	O
octet	O
"	O
format	O
,	O
or	O
a	O
"	O
dotted	B-Protocol
quad	I-Protocol
address	I-Protocol
"	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
address	O
of	O
the	O
loopback	B-Protocol
interface	O
,	O
usually	O
assigned	O
the	O
host	O
name	O
localhost	B-Protocol
,	O
is	O
127.0.0.1	B-Protocol
.	O
</s>
<s>
The	O
first	O
mention	O
of	O
this	O
format	O
in	O
RFC	O
documents	O
was	O
in	O
RFC	O
780	O
for	O
the	O
Mail	B-Protocol
Transfer	I-Protocol
Protocol	I-Protocol
published	O
May	O
1981	O
,	O
in	O
which	O
the	O
IP	O
address	O
was	O
supposed	O
to	O
be	O
enclosed	O
in	O
brackets	O
or	O
represented	O
as	O
a	O
32-bit	O
decimal	B-Application
integer	O
prefixed	O
by	O
a	O
pound	O
sign	O
.	O
</s>
<s>
A	O
table	O
in	O
RFC	O
790	O
(	O
Assigned	O
Numbers	O
)	O
used	O
the	O
dotted	B-Protocol
decimal	I-Protocol
format	O
,	O
zero-padding	O
each	O
number	O
to	O
three	O
digits	O
.	O
</s>
<s>
RFC	O
1123	O
(	O
Requirements	O
for	O
Internet	O
Hosts	O
–	O
Application	O
and	O
Support	O
)	O
of	O
October	O
1989	O
mentions	O
a	O
requirement	O
for	O
host	O
software	O
to	O
accept	O
“	O
IP	O
address	O
in	O
dotted-decimal	B-Protocol
("#.#.#.#"	O
)	O
form	O
”	O
,	O
although	O
it	O
notes	O
“[t]his	O
last	O
requirement	O
is	O
not	O
intended	O
to	O
specify	O
the	O
complete	O
syntactic	O
form	O
for	O
entering	O
a	O
dotted-decimal	B-Protocol
host	O
number	O
”	O
.	O
</s>
<s>
In	O
addition	O
to	O
the	O
basic	O
four-decimals	O
format	O
and	O
32-bit	O
numbers	O
,	O
it	O
also	O
supported	O
intermediate	O
syntax	O
forms	O
of	O
octet.24bits	O
(	O
e.g.	O
</s>
<s>
10.1234567	O
;	O
for	O
Class	B-Protocol
A	I-Protocol
addresses	O
)	O
and	O
octet.octet.16bits	O
(	O
e.g.	O
</s>
<s>
A	O
POSIX-conforming	O
variant	O
of	O
inet_aton	O
,	O
the	O
inet_pton( )	O
function	O
,	O
supports	O
only	O
the	O
four-decimal	O
variant	O
of	O
IP	O
addresses	O
.	O
</s>
<s>
IP	O
addresses	O
in	O
dot-decimal	B-Protocol
notation	I-Protocol
are	O
also	O
presented	O
in	O
CIDR	B-Protocol
notation	I-Protocol
,	O
in	O
which	O
the	O
IP	O
address	O
is	O
suffixed	O
with	O
a	O
slash	O
and	O
a	O
number	O
,	O
used	O
to	O
specify	O
the	O
length	O
of	O
the	O
associated	O
routing	O
prefix	O
.	O
</s>
<s>
For	O
example	O
,	O
127.0.0.1/8	O
specifies	O
that	O
the	O
IP	O
address	O
has	O
an	O
eight-bit	O
routing	O
prefix	O
,	O
and	O
therefore	O
the	O
subnet	O
mask	O
255.0.0.0	O
.	O
</s>
<s>
Object	O
identifiers	O
use	O
a	O
style	O
of	O
dot-decimal	B-Protocol
notation	I-Protocol
to	O
represent	O
an	O
arbitrarily	O
deep	O
hierarchy	O
of	O
objects	O
identified	O
by	O
decimal	B-Application
numbers	O
.	O
</s>
<s>
They	O
may	O
also	O
use	O
textual	O
words	O
separated	O
by	O
dots	O
,	O
like	O
some	O
computer	O
languages	O
(	O
see	O
inheritance	B-Language
)	O
.	O
</s>
<s>
Software	O
releases	O
are	O
often	O
given	O
version	O
numbers	O
in	O
dot-decimal	B-Protocol
notation	I-Protocol
,	O
with	O
the	O
first	O
digit	O
designating	O
major	O
revisions	O
and	O
the	O
smaller	O
ones	O
progressively	O
more	O
minor	O
releases	O
.	O
</s>
<s>
Libraries	O
use	O
notation	O
systems	O
consisting	O
of	O
decimal	B-Application
numbers	O
separated	O
by	O
dots	O
,	O
such	O
as	O
the	O
older	O
Dewey	O
Decimal	B-Application
Classification	O
and	O
the	O
Universal	O
Decimal	B-Application
Classification	O
,	O
to	O
classify	O
books	O
and	O
other	O
works	O
by	O
subject	O
.	O
</s>
<s>
The	O
UDC	O
additionally	O
codes	O
works	O
with	O
multiple	O
dot-decimal	B-Protocol
topics	O
,	O
separated	O
by	O
colons	O
.	O
</s>
<s>
Dot-decimal	B-Protocol
notation	I-Protocol
is	O
often	O
used	O
for	O
sections	O
within	O
a	O
large	O
text	O
.	O
</s>
<s>
Dot-decimal	B-Protocol
notation	I-Protocol
is	O
also	O
used	O
to	O
describe	O
illnesses	O
in	O
a	O
language-neutral	O
way	O
.	O
</s>
