<s>
Data	B-Device
position	I-Device
measurement	I-Device
(	O
DPM	O
)	O
is	O
a	O
copy	B-Application
protection	I-Application
mechanism	O
that	O
operates	O
by	O
measuring	O
the	O
physical	O
location	O
of	O
data	O
on	O
an	O
optical	B-Device
disc	I-Device
.	O
</s>
<s>
DPM	O
was	O
first	O
used	O
publicly	O
in	O
1996	O
by	O
Link	O
Data	O
Security	O
's	O
CD-Cops	B-Operating_System
.	O
</s>
<s>
DPM	O
can	O
be	O
observed	O
and	O
subsequently	O
encoded	O
into	O
a	O
recordable	O
media	O
physical	O
signature	O
(	O
RMPS	B-Device
)	O
.	O
</s>
<s>
In	O
concert	O
with	O
emulation	O
software	O
RMPS	B-Device
can	O
reproduce	O
the	O
effects	O
of	O
DPM	O
thereby	O
appearing	O
as	O
an	O
original	O
disc	O
and	O
fooling	O
the	O
protection	O
mechanism	O
.	O
</s>
<s>
This	O
technique	O
was	O
pioneered	O
by	O
the	O
software	O
Alcohol	B-Application
120%	I-Application
,	O
for	O
which	O
it	O
created	O
the	O
.mds	B-General_Concept
file	O
format	O
.	O
</s>
