<s>
A	O
header	B-Error_Name
check	I-Error_Name
sequence	I-Error_Name
(	O
HCS	O
)	O
is	O
an	O
error	B-Error_Name
checking	I-Error_Name
feature	O
for	O
various	O
header	B-General_Concept
data	O
structures	O
,	O
such	O
as	O
in	O
the	O
Media	B-Protocol
Access	I-Protocol
Control	I-Protocol
(	O
MAC	O
)	O
header	B-General_Concept
of	O
Ethernet	O
.	O
</s>
<s>
It	O
may	O
consist	O
of	O
a	O
cyclic	O
redundancy	O
check	O
(	O
CRC	O
)	O
of	O
the	O
frame	B-Protocol
,	O
obtained	O
as	O
the	O
remainder	O
of	O
the	O
division	O
(	O
modulo	O
2	O
)	O
by	O
the	O
generator	O
polynomial	O
multiplied	O
by	O
the	O
content	O
of	O
the	O
header	B-General_Concept
excluding	O
the	O
HCS	O
field	O
.	O
</s>
<s>
The	O
HCS	O
can	O
be	O
one	O
octet	O
long	O
,	O
as	O
in	O
WiMAX	O
,	O
or	O
a	O
16-bit	O
value	O
for	O
cable	B-Device
modems	I-Device
.	O
</s>
