<s>
CD-RW	O
(	O
Compact	O
Disc-Rewritable	O
)	O
is	O
a	O
digital	O
optical	B-Device
disc	I-Device
storage	B-General_Concept
format	O
introduced	O
in	O
1997	O
.	O
</s>
<s>
CD-ROM	B-Device
drives	O
with	O
a	O
"	O
MultiRead	O
"	O
certification	O
are	O
compatible	O
.	O
</s>
<s>
Erasure	O
methods	O
include	O
full	O
blanking	O
where	O
the	O
entire	O
surface	O
of	O
the	O
disc	O
is	O
erased	O
and	O
fast	O
blanking	O
where	O
only	O
metadata	O
areas	O
,	O
such	O
as	O
PMA	O
,	O
TOC	B-Application
and	O
pregap	O
,	O
are	O
cleared	O
.	O
</s>
<s>
CD-RWs	O
can	O
sustain	O
fewer	O
re-writes	O
compared	O
to	O
other	O
storage	B-General_Concept
media	I-General_Concept
(	O
ca	O
.	O
</s>
<s>
for	O
CD	B-Application
authoring	I-Application
)	O
,	O
temporary	O
backups	O
,	O
and	O
as	O
a	O
middle-ground	O
between	O
online	O
and	O
offline	O
storage	B-General_Concept
schemes	O
.	O
</s>
<s>
Before	O
CD-RW	O
technology	O
,	O
in	O
1990	O
a	O
standard	O
for	O
magneto-optical	B-Device
recordable	O
and	O
erasable	O
CDs	O
called	O
CD-MO	O
was	O
introduced	O
and	O
set	O
in	O
the	O
Orange	O
Book	O
,	O
part	O
1	O
as	O
a	O
CD	O
with	O
a	O
magneto-optical	B-Device
recording	O
layer	O
.	O
</s>
<s>
The	O
CD-MO	O
standard	O
allowed	O
for	O
an	O
optional	O
non-erasable	O
zone	O
on	O
the	O
disc	O
that	O
could	O
be	O
read	O
by	O
CD-ROM	B-Device
units	O
.	O
</s>
<s>
Data	B-General_Concept
recording	I-General_Concept
(	O
and	O
erasing	O
)	O
was	O
achieved	O
by	O
heating	O
the	O
magneto-optical	B-Device
layer	O
's	O
material	O
(	O
e.g.	O
</s>
<s>
DyFeCo	O
or	O
less	O
often	O
TbFeCo	O
or	O
GdFeCo	O
)	O
to	O
its	O
Curie	O
point	O
and	O
then	O
using	O
a	O
magnetic	O
field	O
to	O
write	O
the	O
new	O
data	O
,	O
in	O
a	O
manner	O
essentially	O
identical	O
to	O
Sony	O
's	O
MiniDisc	O
and	O
other	O
magneto-optical	B-Device
formats	O
.	O
</s>
<s>
The	O
rewrite	O
could	O
only	O
be	O
read	O
in	O
special	O
drives	O
and	O
was	O
incompatible	O
with	O
non-magneto-optical	O
enabled	O
drives	O
.	O
</s>
<s>
Some	O
magneto-optical	B-Device
drives	I-Device
and	O
media	O
with	O
the	O
same	O
form	O
factor	O
do	O
n't	O
have	O
this	O
limitation	O
.	O
</s>
<s>
Other	O
magneto-optical	B-Device
media	O
,	O
unbound	O
by	O
limitations	O
of	O
the	O
typical	O
CD-ROM	B-Device
filesystems	O
,	O
replaced	O
the	O
CD-MO	O
.	O
</s>
<s>
In	O
addition	O
a	O
frequency	B-Application
modulation	I-Application
is	O
applied	O
to	O
provide	O
the	O
recorder	O
with	O
an	O
absolute	O
time	O
reference	O
.	O
</s>
<s>
PMA	O
:	O
The	O
Program	B-Application
Memory	I-Application
Area	I-Application
of	O
a	O
CD-RW	O
is	O
a	O
record	O
of	O
the	O
data	O
recorded	O
on	O
an	O
unfinished	O
or	O
unfinalized	O
disc	O
.	O
</s>
<s>
It	O
is	O
used	O
as	O
a	O
transition	O
TOC	B-Application
while	O
the	O
session	O
is	O
still	O
open	O
.	O
</s>
<s>
Each	O
session	O
on	O
a	O
multi-session	O
disc	O
has	O
a	O
corresponding	O
lead-in	O
,	O
PMA	O
,	O
PA	O
and	O
lead-out	B-Application
.	O
</s>
<s>
When	O
the	O
session	O
is	O
closed	O
TOC	B-Application
information	O
in	O
the	O
PMA	O
is	O
written	O
into	O
a	O
lead-in	O
area	O
and	O
the	O
PCA	O
and	O
PMA	O
are	O
logically	O
eliminated	O
.	O
</s>
<s>
The	O
lead-out	B-Application
is	O
created	O
to	O
mark	O
the	O
end	O
of	O
the	O
data	O
in	O
the	O
session	O
.	O
</s>
<s>
Many	O
half-height	B-Device
CD	O
and	O
DVD	O
writers	O
released	O
between	O
2004	O
and	O
2010	O
,	O
including	O
the	O
TSSTcorp	O
SH-M522	O
combo	B-Device
drive	I-Device
(	O
2004	O
)	O
,	O
Pioneer	O
DVR-110D	O
(	O
2005	O
)	O
,	O
Hitachi-LG	O
GSA-4167	O
(	O
2005	O
)	O
,	O
TSSTcorp	O
SH-S182/S183	O
(	O
2006	O
)	O
and	O
SH-S203/TS	O
-H653B	O
(	O
2007	O
)	O
have	O
officially	O
adapted	O
support	O
for	O
CD-RW	O
UltraSpeed	O
Plus	O
(	O
32×	O
Z-CLV	O
)	O
,	O
while	O
more	O
recent	O
DVD	O
writers	O
such	O
as	O
the	O
SH-224DB	O
(	O
2013	O
)	O
and	O
Blu-Ray	O
writers	O
such	O
as	O
the	O
LG	O
BE16NU50	O
(	O
2016	O
)	O
have	O
downgraded	O
the	O
backwards	B-General_Concept
compatibility	I-General_Concept
to	O
CD-RW	O
UltraSpeed	O
(	O
24×	O
Z-CLV	O
)	O
.	O
</s>
<s>
Slim	O
type	O
optical	O
drives	O
are	O
subject	O
to	O
physical	O
limitations	O
,	O
thus	O
are	O
not	O
able	O
to	O
attain	O
rotation	O
speeds	O
of	O
half-height	B-Device
(	O
desktop	O
)	O
optical	O
drives	O
.	O
</s>
