<s>
In	O
information	B-General_Concept
technology	I-General_Concept
,	O
a	O
trailer	B-Device
or	O
footer	O
refers	O
to	O
supplemental	O
data	O
(	O
metadata	O
)	O
placed	O
at	O
the	O
end	O
of	O
a	O
block	O
of	O
data	O
being	O
stored	O
or	O
transmitted	O
,	O
which	O
may	O
contain	O
information	O
for	O
the	O
handling	O
of	O
the	O
data	O
block	O
,	O
or	O
simply	O
mark	O
the	O
block	O
's	O
end	O
.	O
</s>
<s>
In	O
data	O
transmission	O
,	O
the	O
data	O
following	O
the	O
end	O
of	O
the	O
header	B-General_Concept
and	O
preceding	O
the	O
start	O
of	O
the	O
trailer	B-Device
is	O
called	O
the	O
payload	O
or	O
body	O
.	O
</s>
<s>
It	O
is	O
vital	O
that	O
trailer	B-Device
composition	O
follow	O
a	O
clear	O
and	O
unambiguous	O
specification	B-Application
or	O
format	O
,	O
to	O
allow	O
for	O
parsing	B-Language
.	O
</s>
<s>
If	O
a	O
trailer	B-Device
is	O
not	O
removed	O
properly	O
,	O
or	O
part	O
of	O
the	O
payload	O
is	O
removed	O
thinking	O
it	O
is	O
a	O
trailer	B-Device
,	O
it	O
can	O
cause	O
confusion	O
.	O
</s>
<s>
In	O
data	O
transfer	O
,	O
the	O
OSI	O
model	O
's	O
data	B-Protocol
link	I-Protocol
layer	I-Protocol
adds	O
a	O
trailer	B-Device
at	O
the	O
end	O
of	O
frames	B-Protocol
of	O
the	O
data	B-Protocol
encapsulation	I-Protocol
.	O
</s>
