<s>
In	O
a	O
multichannel	O
transmission	O
system	O
,	O
drop	B-Protocol
and	I-Protocol
insert	I-Protocol
is	O
a	O
process	O
that	O
diverts	O
(	O
drop	O
)	O
a	O
portion	O
of	O
the	O
multiplexed	O
aggregate	O
signal	O
at	O
an	O
intermediate	O
point	O
,	O
and	O
introduces	O
(	O
insert	O
)	O
a	O
different	O
signal	O
for	O
subsequent	O
transmission	O
in	O
the	O
same	O
position	O
.	O
</s>
<s>
Drop	B-Protocol
and	I-Protocol
insert	I-Protocol
is	O
practiced	O
,	O
for	O
example	O
,	O
in	O
time-division	B-Protocol
multiplexing	I-Protocol
(	O
TDM	O
)	O
when	O
a	O
time	O
slot	O
or	O
frequency	O
band	O
is	O
replaced	O
from	O
another	O
source	O
.	O
</s>
