<s>
Media	B-General_Concept
Descriptor	I-General_Concept
File	I-General_Concept
(	O
MDF	O
)	O
is	O
a	O
proprietary	O
disc	B-Application
image	I-Application
file	O
format	O
developed	O
for	O
Alcohol	B-Application
120%	I-Application
,	O
an	O
optical	B-Device
disc	I-Device
authoring	O
program	O
.	O
</s>
<s>
Daemon	B-Application
Tools	I-Application
,	O
CDemu	B-Language
,	O
MagicISO	B-Application
,	O
PowerDVD	O
,	O
and	O
WinCDEmu	B-Application
can	O
also	O
read	O
the	O
MDF	O
format	O
.	O
</s>
<s>
A	O
disc	B-Application
image	I-Application
is	O
a	O
computer	B-Operating_System
file	I-Operating_System
replica	O
of	O
the	O
computer	B-Operating_System
files	I-Operating_System
and	O
file	B-Application
system	I-Application
of	O
an	O
optical	B-Device
disc	I-Device
.	O
</s>
<s>
Unlike	O
an	O
ISO	B-General_Concept
image	I-General_Concept
,	O
a	O
Media	B-General_Concept
Descriptor	I-General_Concept
File	I-General_Concept
can	O
contain	O
multiple	O
layers	O
(	O
as	O
used	O
in	O
dual-layer	O
recording	O
)	O
and	O
multiple	O
optical	B-Device
disc	I-Device
tracks	O
.	O
</s>
<s>
Like	O
the	O
IMG	B-General_Concept
file	I-General_Concept
format	I-General_Concept
,	O
a	O
Media	B-General_Concept
Descriptor	I-General_Concept
File	I-General_Concept
is	O
a	O
"	O
raw	O
"	O
image	O
of	O
an	O
optical	B-Device
disc	I-Device
.	O
</s>
<s>
The	O
word	O
raw	O
implies	O
that	O
the	O
copy	O
is	O
precise	O
,	O
bit-for-bit	O
,	O
including	O
(	O
where	O
appropriate	O
)	O
file-system	B-Application
metadata	O
.	O
</s>
<s>
A	O
Media	B-General_Concept
Descriptor	I-General_Concept
File	I-General_Concept
may	O
be	O
accompanied	O
by	O
a	O
Media	O
Descriptor	O
Sidecar	O
file	O
.	O
</s>
<s>
This	O
optional	O
binary	O
file	O
(	O
with	O
file	O
extension	O
.mds	B-General_Concept
)	O
contains	O
metadata	O
about	O
an	O
imaged	O
optical	B-Device
disc	I-Device
,	O
including	O
a	O
delineation	O
of	O
where	O
disc	O
layers	O
begin	O
and	O
end	O
(	O
"	O
layer	O
breaks	O
"	O
)	O
,	O
and	O
which	O
portions	O
of	O
the	O
MDF	O
belong	O
in	O
which	O
disc	O
layer	O
.	O
</s>
<s>
The	O
MDS	B-General_Concept
file	I-General_Concept
also	O
stores	O
the	O
location	O
and	O
value	O
of	O
the	O
layer	O
breach	O
bit	O
,	O
a	O
CD/DVD	O
copy	O
protection	O
mechanism	O
.	O
</s>
<s>
The	O
MDS	B-General_Concept
file	I-General_Concept
is	O
comparable	O
to	O
the	O
CloneCD	B-Application
Control	O
File	O
and	O
cue	O
sheet	O
(	O
.cue	O
)	O
file	O
formats	O
.	O
</s>
<s>
However	O
,	O
their	O
capabilities	O
are	O
not	O
identical	O
;	O
also	O
the	O
cue	O
sheet	O
is	O
a	O
text	B-General_Concept
file	I-General_Concept
format	I-General_Concept
.	O
</s>
<s>
Alcohol	O
120%'s	O
MDF/MDS	O
format	O
is	O
one	O
of	O
the	O
few	O
formats	O
besides	O
Nero	B-Application
's	I-Application
NRG	B-General_Concept
,	O
BIN/CUE	O
and	O
CloneCD	B-Application
's	O
CCD/IMG/SUB	O
disc	B-Application
image	I-Application
formats	O
to	O
support	O
Mixed	O
Mode	O
CDs	O
which	O
contain	O
audio	O
CD	O
tracks	O
as	O
well	O
as	O
data	O
tracks	O
.	O
</s>
