<s>
In	O
data	O
transmission	O
and	O
telecommunication	O
,	O
bit	B-Protocol
stuffing	I-Protocol
(	O
also	O
known	O
—	O
uncommonly	O
—	O
as	O
positive	B-Protocol
justification	I-Protocol
)	O
is	O
the	O
insertion	O
of	O
non-information	O
bits	O
into	O
data	O
.	O
</s>
<s>
Bit	B-Protocol
stuffing	I-Protocol
is	O
used	O
for	O
various	O
purposes	O
,	O
such	O
as	O
for	O
bringing	O
bit	O
streams	O
that	O
do	O
not	O
necessarily	O
have	O
the	O
same	O
or	O
rationally	O
related	O
bit	O
rates	O
up	O
to	O
a	O
common	O
rate	O
,	O
or	O
to	O
fill	O
buffers	O
or	O
frames	B-Protocol
.	O
</s>
<s>
Bit	B-Protocol
stuffing	I-Protocol
may	O
be	O
used	O
to	O
synchronize	O
several	O
channels	O
before	O
multiplexing	B-Architecture
or	O
to	O
rate-match	O
two	O
single	O
channels	O
to	O
each	O
other	O
.	O
</s>
<s>
Another	O
use	O
of	O
bit	B-Protocol
stuffing	I-Protocol
is	O
for	O
run	B-Protocol
length	I-Protocol
limited	I-Protocol
coding	I-Protocol
:	O
to	O
limit	O
the	O
number	O
of	O
consecutive	O
bits	O
of	O
the	O
same	O
value	O
in	O
the	O
data	O
to	O
be	O
transmitted	O
.	O
</s>
<s>
Bit	B-Protocol
stuffing	I-Protocol
does	O
not	O
ensure	O
that	O
the	O
payload	O
is	O
intact	O
(	O
i.e.	O
</s>
<s>
Error	B-Error_Name
detection	I-Error_Name
and	I-Error_Name
correction	I-Error_Name
techniques	O
are	O
used	O
to	O
check	O
the	O
frame	O
for	O
corruption	O
after	O
its	O
delivery	O
and	O
,	O
if	O
necessary	O
,	O
the	O
frame	O
will	O
be	O
re-sent	O
.	O
</s>
<s>
In	O
this	O
case	O
,	O
bit	B-Protocol
stuffing	I-Protocol
is	O
most	O
easily	O
described	O
as	O
the	O
insertion	O
of	O
a	O
0	O
bit	O
after	O
a	O
long	O
run	O
of	O
1	O
bits	O
.	O
</s>
<s>
It	O
was	O
popularized	O
by	O
IBM	O
's	O
SDLC	B-Protocol
(	O
later	O
renamed	O
HDLC	O
)	O
,	O
and	O
is	O
also	O
used	O
in	O
Low	O
-	O
and	O
full-speed	O
USB	B-Protocol
.	O
</s>
<s>
By	O
inserting	O
a	O
0	O
after	O
five	O
(	O
SDLC	B-Protocol
)	O
or	O
six	O
(	O
USB	B-Protocol
)	O
consecutive	O
1	O
bits	O
the	O
transmitter	O
guarantees	O
a	O
maximum	O
of	O
six	O
(	O
SDLC	B-Protocol
)	O
or	O
seven	O
(	O
USB	B-Protocol
)	O
bit	O
times	O
between	O
transitions	O
.	O
</s>
<s>
In	O
SDLC	B-Protocol
the	O
transmitted	O
bit	O
sequence	O
"	O
01111110	O
"	O
containing	O
six	O
adjacent	O
1	O
bits	O
is	O
the	O
Flag	O
byte	O
.	O
</s>
<s>
Bit	B-Protocol
stuffing	I-Protocol
ensures	O
that	O
this	O
pattern	O
can	O
never	O
occur	O
in	O
normal	O
data	O
,	O
so	O
it	O
can	O
be	O
used	O
as	O
a	O
marker	O
for	O
the	O
beginning	O
and	O
end	O
of	O
the	O
frame	O
without	O
any	O
possibility	O
of	O
being	O
confused	O
with	O
normal	O
data	O
.	O
</s>
<s>
The	O
main	O
disadvantage	O
of	O
bit-stuffing	B-Protocol
is	O
that	O
the	O
code	O
rate	O
is	O
unpredictable	O
;	O
it	O
depends	O
on	O
the	O
data	O
being	O
transmitted	O
.	O
</s>
