<s>
In	O
telecommunication	O
,	O
a	O
variable	B-General_Concept
length	I-General_Concept
buffer	I-General_Concept
or	O
elastic	B-General_Concept
buffer	I-General_Concept
is	O
a	O
buffer	O
into	O
which	O
data	O
may	O
be	O
entered	O
at	O
one	O
rate	O
and	O
removed	O
at	O
another	O
rate	O
without	O
changing	O
the	O
data	O
sequence	O
.	O
</s>
<s>
Most	O
first-in	B-Operating_System
first-out	I-Operating_System
(	O
FIFO	B-Operating_System
)	O
storage	B-General_Concept
devices	I-General_Concept
are	O
variable-length	B-General_Concept
buffers	I-General_Concept
in	O
that	O
the	O
input	O
rate	O
may	O
be	O
variable	O
while	O
the	O
output	B-General_Concept
rate	O
is	O
constant	O
or	O
the	O
output	B-General_Concept
rate	O
may	O
be	O
variable	O
while	O
the	O
input	O
rate	O
is	O
constant	O
.	O
</s>
<s>
Various	O
clocking	O
and	O
control	O
systems	O
are	O
used	O
to	O
allow	O
control	O
of	O
underflow	O
or	O
overflow	B-General_Concept
conditions	O
.	O
</s>
