<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
the	O
sign	B-Algorithm
bit	I-Algorithm
is	O
a	O
bit	O
in	O
a	O
signed	B-Algorithm
number	I-Algorithm
representation	I-Algorithm
that	O
indicates	O
the	O
sign	O
of	O
a	O
number	O
.	O
</s>
<s>
Although	O
only	O
signed	B-Algorithm
numeric	B-Algorithm
data	O
types	O
have	O
a	O
sign	B-Algorithm
bit	I-Algorithm
,	O
it	O
is	O
invariably	O
located	O
in	O
the	O
most	O
significant	O
bit	O
position	O
,	O
so	O
the	O
term	O
may	O
be	O
used	O
interchangeably	O
with	O
"	O
most	O
significant	O
bit	O
"	O
in	O
some	O
contexts	O
.	O
</s>
<s>
Almost	O
always	O
,	O
if	O
the	O
sign	B-Algorithm
bit	I-Algorithm
is	O
0	O
,	O
the	O
number	O
is	O
non-negative	O
(	O
positive	O
or	O
zero	O
)	O
.	O
</s>
<s>
If	O
the	O
sign	B-Algorithm
bit	I-Algorithm
is	O
1	O
then	O
the	O
number	O
is	O
negative	O
,	O
although	O
formats	O
other	O
than	O
two	B-General_Concept
's	I-General_Concept
complement	I-General_Concept
integers	O
allow	O
a	O
signed	B-Algorithm
zero	I-Algorithm
:	O
distinct	O
"	O
positive	O
zero	O
"	O
and	O
"	O
negative	B-Algorithm
zero	I-Algorithm
"	O
representations	O
,	O
the	O
latter	O
of	O
which	O
does	O
not	O
correspond	O
to	O
the	O
mathematical	O
concept	O
of	O
a	O
negative	O
number	O
.	O
</s>
<s>
In	O
the	O
two	B-General_Concept
's	I-General_Concept
complement	I-General_Concept
representation	O
,	O
the	O
sign	B-Algorithm
bit	I-Algorithm
has	O
the	O
weight	O
where	O
is	O
the	O
number	O
of	O
bits	O
.	O
</s>
<s>
In	O
the	O
ones	O
 '	O
complement	O
representation	O
,	O
the	O
most	O
negative	O
value	O
is	O
,	O
but	O
there	O
are	O
two	B-Algorithm
representations	I-Algorithm
of	I-Algorithm
zero	I-Algorithm
,	O
one	O
for	O
each	O
value	O
of	O
the	O
sign	B-Algorithm
bit	I-Algorithm
.	O
</s>
<s>
In	O
a	O
sign-and-magnitude	O
representation	O
of	O
numbers	O
,	O
the	O
value	O
of	O
the	O
sign	B-Algorithm
bit	I-Algorithm
determines	O
whether	O
the	O
numerical	O
value	O
is	O
positive	O
or	O
negative	O
.	O
</s>
<s>
Floating-point	B-Algorithm
numbers	I-Algorithm
,	O
such	O
as	O
IEEE	O
format	O
,	O
IBM	B-Device
format	I-Device
,	O
VAX	B-Device
format	O
,	O
and	O
even	O
the	O
format	O
used	O
by	O
the	O
Zuse	B-Device
Z1	I-Device
and	O
Z3	B-Device
use	O
a	O
sign-and-magnitude	O
representation	O
.	O
</s>
<s>
When	O
using	O
a	O
complement	O
representation	O
,	O
to	O
convert	O
a	O
signed	B-Algorithm
number	O
to	O
a	O
wider	O
format	O
the	O
additional	O
bits	O
must	O
be	O
filled	O
with	O
copies	O
of	O
the	O
sign	B-Algorithm
bit	I-Algorithm
in	O
order	O
to	O
preserve	O
its	O
numerical	O
value	O
,	O
a	O
process	O
called	O
sign	O
extension	O
or	O
sign	O
propagation	O
.	O
</s>
