<s>
In	O
computing	O
,	O
a	O
line	O
is	O
a	O
unit	O
of	O
organization	O
for	O
text	B-General_Concept
files	I-General_Concept
.	O
</s>
<s>
Depending	O
on	O
the	O
file	B-Application
system	I-Application
or	O
operating	B-General_Concept
system	I-General_Concept
being	O
used	O
the	O
number	O
of	O
characters	O
on	O
a	O
line	O
may	O
either	O
be	O
predetermined	O
or	O
fixed	O
,	O
or	O
the	O
length	O
may	O
vary	O
from	O
line	O
to	O
line	O
.	O
</s>
<s>
Fixed-length	O
lines	O
are	O
sometimes	O
called	O
records	B-General_Concept
.	O
</s>
<s>
A	O
blank	B-General_Concept
line	I-General_Concept
usually	O
refers	O
to	O
a	O
line	O
containing	O
zero	O
characters	O
(	O
not	O
counting	O
any	O
end-of-line	O
characters	O
)	O
;	O
though	O
it	O
may	O
also	O
refer	O
to	O
any	O
line	O
that	O
does	O
not	O
contain	O
any	O
visible	O
characters	O
(	O
consisting	O
only	O
of	O
whitespace	O
)	O
.	O
</s>
<s>
Some	O
tools	O
that	O
operate	O
on	O
text	B-General_Concept
files	I-General_Concept
(	O
e.g.	O
,	O
editors	B-Application
)	O
provide	O
a	O
mechanism	O
to	O
reference	O
lines	O
by	O
their	O
line	B-Application
number	I-Application
.	O
</s>
