<s>
ISO	B-Application
9660	I-Application
(	O
also	O
known	O
as	O
ECMA-119	B-Application
)	O
is	O
a	O
file	B-Application
system	I-Application
for	O
optical	B-Device
disc	I-Device
media	O
.	O
</s>
<s>
The	O
file	B-Application
system	I-Application
is	O
an	O
international	O
standard	O
available	O
from	O
the	O
International	O
Organization	O
for	O
Standardization	O
(	O
ISO	B-General_Concept
)	O
.	O
</s>
<s>
Since	O
the	O
specification	O
is	O
available	O
for	O
anybody	O
to	O
purchase	O
,	O
implementations	O
have	O
been	O
written	O
for	O
many	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
ISO	B-Application
9660	I-Application
traces	O
its	O
roots	O
to	O
the	O
High	O
Sierra	O
Format	O
,	O
which	O
arranged	O
file	O
information	O
in	O
a	O
dense	O
,	O
sequential	O
layout	O
to	O
minimize	O
nonsequential	O
access	O
by	O
using	O
a	O
hierarchical	O
(	O
eight	O
levels	O
of	O
directories	O
deep	O
)	O
tree	O
file	B-Application
system	I-Application
arrangement	O
,	O
similar	O
to	O
UNIX	B-Application
and	O
FAT	B-Application
.	O
</s>
<s>
High	O
Sierra	O
was	O
adopted	O
in	O
December	O
1986	O
(	O
with	O
changes	O
)	O
as	O
an	O
international	O
standard	O
by	O
Ecma	O
International	O
as	O
ECMA-119	B-Application
and	O
submitted	O
for	O
fast	O
tracking	O
to	O
the	O
ISO	B-General_Concept
,	O
where	O
it	O
was	O
eventually	O
accepted	O
as	O
ISO	B-General_Concept
9660:1988	O
.	O
</s>
<s>
The	O
first	O
16	O
sectors	O
of	O
the	O
file	B-Application
system	I-Application
are	O
empty	O
and	O
reserved	O
for	O
other	O
uses	O
.	O
</s>
<s>
The	O
rest	O
begins	O
with	O
a	O
volume	O
descriptor	O
set	O
(	O
a	O
header	B-General_Concept
block	O
which	O
describes	O
the	O
subsequent	O
layout	O
)	O
and	O
then	O
the	O
path	O
tables	O
,	O
directories	O
and	O
files	B-Operating_System
on	O
the	O
disc	O
.	O
</s>
<s>
An	O
ISO	B-Application
9660	I-Application
compliant	O
disc	O
must	O
contain	O
at	O
least	O
one	O
primary	O
volume	O
descriptor	O
describing	O
the	O
file	B-Application
system	I-Application
and	O
a	O
volume	O
descriptor	O
set	O
terminator	O
which	O
is	O
a	O
volume	O
descriptor	O
that	O
marks	O
the	O
end	O
of	O
the	O
descriptor	O
set	O
.	O
</s>
<s>
Other	O
fields	O
contain	O
metadata	O
such	O
as	O
the	O
volume	O
's	O
name	O
and	O
creator	O
,	O
along	O
with	O
the	O
size	O
and	O
number	O
of	O
logical	O
blocks	O
used	O
by	O
the	O
file	B-Application
system	I-Application
.	O
</s>
<s>
For	O
each	O
directory	O
in	O
the	O
image	O
,	O
the	O
path	O
table	O
provides	O
the	O
directory	O
identifier	O
,	O
the	O
location	O
of	O
the	O
extent	B-Application
in	O
which	O
the	O
directory	O
is	O
recorded	O
,	O
the	O
length	O
of	O
any	O
extended	B-Application
attributes	I-Application
associated	O
with	O
the	O
directory	O
,	O
and	O
the	O
index	O
of	O
its	O
parent	O
directory	O
path	O
table	O
entry	O
.	O
</s>
<s>
There	O
are	O
several	O
extensions	O
to	O
ISO	B-Application
9660	I-Application
that	O
relax	O
some	O
of	O
its	O
limitations	O
.	O
</s>
<s>
Notable	O
examples	O
include	O
Rock	O
Ridge	O
(	O
Unix-style	B-Operating_System
permissions	O
and	O
longer	O
names	O
)	O
,	O
Joliet	O
(	O
Unicode	O
,	O
allowing	O
non-Latin	O
scripts	O
to	O
be	O
used	O
)	O
,	O
El	B-Device
Torito	I-Device
(	O
enables	O
CDs	O
to	O
be	O
bootable	B-Operating_System
)	O
and	O
the	O
Apple	O
ISO	B-Application
9660	I-Application
Extensions	O
(	O
file	O
characteristics	O
specific	O
to	O
the	O
classic	B-Application
Mac	I-Application
OS	I-Application
and	O
macOS	B-Application
,	O
such	O
as	O
resource	B-Operating_System
forks	I-Operating_System
,	O
file	O
backup	O
date	O
and	O
more	O
)	O
.	O
</s>
<s>
Compact	O
discs	O
were	O
originally	O
developed	O
for	O
recording	O
musical	O
data	O
,	O
but	O
soon	O
were	O
used	O
for	O
storing	O
additional	O
digital	O
data	O
types	O
because	O
they	O
were	O
equally	O
effective	O
for	O
archival	O
mass	B-Device
data	I-Device
storage	I-Device
.	O
</s>
<s>
Called	O
CD-ROMs	B-Device
,	O
the	O
lowest	O
level	O
format	O
for	O
these	O
type	O
of	O
compact	O
discs	O
was	O
defined	O
in	O
the	O
Yellow	B-Device
Book	I-Device
specification	O
in	O
1983	O
.	O
</s>
<s>
However	O
,	O
this	O
book	O
did	O
not	O
define	O
any	O
format	O
for	O
organizing	O
data	O
on	O
CD-ROMs	B-Device
into	O
logical	O
units	O
such	O
as	O
files	B-Operating_System
,	O
which	O
led	O
to	O
every	O
CD-ROM	B-Device
maker	O
creating	O
its	O
own	O
format	O
.	O
</s>
<s>
In	O
order	O
to	O
develop	O
a	O
CD-ROM	B-Device
file	B-Application
system	I-Application
standard	O
(	O
Z39.60	O
-	O
Volume	O
and	O
File	O
Structure	O
of	O
CDROM	B-Device
for	O
Information	O
Interchange	O
)	O
,	O
the	O
National	O
Information	O
Standards	O
Organization	O
(	O
NISO	O
)	O
set	O
up	O
Standards	O
Committee	O
SC	O
EE	O
(	O
Compact	O
Disc	O
Data	O
Format	O
)	O
in	O
July	O
1985	O
.	O
</s>
<s>
Present	O
at	O
the	O
meeting	O
were	O
representatives	O
from	O
Apple	O
Computer	O
,	O
AT&T	O
,	O
Digital	O
Equipment	O
Corporation	O
(	O
DEC	O
)	O
,	O
Hitachi	O
,	O
LaserData	O
,	O
Microware	B-Operating_System
,	O
Microsoft	O
,	O
3M	O
,	O
Philips	O
,	O
Reference	O
Technology	O
Inc.	O
,	O
Sony	O
Corporation	O
,	O
TMS	O
Inc.	O
,	O
VideoTools	O
(	O
later	O
Meridian	O
)	O
,	O
Xebec	O
,	O
and	O
Yelick	O
.	O
</s>
<s>
The	O
meeting	O
report	O
evolved	O
from	O
the	O
Yellow	B-Device
Book	I-Device
CD-ROM	B-Device
standard	O
,	O
which	O
was	O
so	O
open	O
ended	O
it	O
was	O
leading	O
to	O
diversification	O
and	O
creation	O
of	O
many	O
incompatible	O
data	O
storage	O
methods	O
.	O
</s>
<s>
The	O
High	O
Sierra	O
Group	O
Proposal	O
(	O
HSGP	O
)	O
was	O
released	O
in	O
May	O
1986	O
,	O
defining	O
a	O
file	B-Application
system	I-Application
for	O
CD-ROMs	B-Device
commonly	O
known	O
as	O
the	O
High	O
Sierra	O
Format	O
.	O
</s>
<s>
With	O
some	O
changes	O
,	O
this	O
led	O
to	O
the	O
issue	O
of	O
the	O
initial	O
edition	O
of	O
the	O
ECMA-119	B-Application
standard	O
in	O
December	O
1986	O
.	O
</s>
<s>
The	O
ECMA	O
submitted	O
their	O
standard	O
to	O
the	O
International	O
Standards	O
Organization	O
(	O
ISO	B-General_Concept
)	O
for	O
fast	O
tracking	O
,	O
where	O
it	O
was	O
further	O
refined	O
into	O
the	O
ISO	B-Application
9660	I-Application
standard	O
.	O
</s>
<s>
For	O
compatibility	O
the	O
second	O
edition	O
of	O
ECMA-119	B-Application
was	O
revised	O
to	O
be	O
equivalent	O
to	O
ISO	B-Application
9660	I-Application
in	O
December	O
1987	O
.	O
</s>
<s>
The	O
main	O
changes	O
from	O
the	O
High	O
Sierra	O
Format	O
in	O
the	O
ECMA-119	B-Application
and	O
ISO	B-Application
9660	I-Application
standards	O
were	O
international	O
extensions	O
to	O
allow	O
the	O
format	O
to	O
work	O
better	O
on	O
non-US	O
markets	O
.	O
</s>
<s>
It	O
was	O
withdrawn	O
before	O
final	O
approval	O
,	O
in	O
favour	O
of	O
ISO	B-Application
9660	I-Application
.	O
</s>
<s>
In	O
2013	O
,	O
ISO	B-General_Concept
published	O
Amendment	O
1	O
to	O
the	O
ISO	B-Application
9660	I-Application
standard	O
,	O
introducing	O
new	O
data	O
structures	O
and	O
relaxed	O
file	O
name	O
rules	O
intended	O
to	O
"	O
bring	O
harmonization	O
between	O
ISO	B-Application
9660	I-Application
and	O
widely	O
used	O
'	O
Joliet	O
Specification	O
 '	O
.	O
"	O
</s>
<s>
In	O
December	O
2017	O
,	O
a	O
3rd	O
Edition	O
of	O
ECMA-119	B-Application
was	O
published	O
that	O
is	O
technically	O
identical	O
with	O
ISO	B-Application
9660	I-Application
,	O
Amendment	O
1	O
.	O
</s>
<s>
In	O
2020	O
,	O
ISO	B-General_Concept
published	O
Amendment	O
2	O
,	O
which	O
adds	O
some	O
minor	O
clarifying	O
matter	O
,	O
but	O
does	O
not	O
add	O
or	O
correct	O
any	O
technical	O
information	O
of	O
the	O
standard	O
.	O
</s>
<s>
The	O
following	O
is	O
the	O
rough	O
overall	O
structure	O
of	O
the	O
ISO	B-Application
9660	I-Application
file	B-Application
system	I-Application
.	O
</s>
<s>
The	O
system	O
area	O
,	O
the	O
first	O
32,768	O
data	O
bytes	O
of	O
the	O
disc	O
(	O
16	O
sectors	O
of	O
2,048	O
bytes	O
each	O
)	O
,	O
is	O
unused	O
by	O
ISO	B-Application
9660	I-Application
and	O
therefore	O
available	O
for	O
other	O
uses	O
.	O
</s>
<s>
While	O
it	O
is	O
suggested	O
that	O
they	O
are	O
reserved	O
for	O
use	O
by	O
bootable	B-Operating_System
media	I-Operating_System
,	O
a	O
CD-ROM	B-Device
may	O
contain	O
an	O
alternative	O
file	B-Application
system	I-Application
descriptor	O
in	O
this	O
area	O
,	O
and	O
it	O
is	O
often	O
used	O
by	O
hybrid	B-Application
CDs	I-Application
to	O
offer	O
classic	O
Mac	O
OS-specific	O
and	O
macOS-specific	O
content	O
.	O
</s>
<s>
These	O
collectively	O
act	O
as	O
a	O
header	B-General_Concept
for	O
the	O
data	O
area	O
,	O
describing	O
its	O
content	O
(	O
similar	O
to	O
the	O
BIOS	B-Device
parameter	I-Device
block	I-Device
used	O
by	O
FAT	B-Application
,	O
HPFS	B-Application
and	O
NTFS	B-Application
formatted	O
disks	O
)	O
.	O
</s>
<s>
An	O
ISO	B-Application
9660	I-Application
compliant	O
disc	O
must	O
contain	O
at	O
least	O
one	O
primary	O
volume	O
descriptor	O
describing	O
the	O
file	B-Application
system	I-Application
and	O
a	O
volume	O
descriptor	O
set	O
terminator	O
for	O
indicating	O
the	O
end	O
of	O
the	O
descriptor	O
sequence	O
.	O
</s>
<s>
The	O
size	O
of	O
the	O
logical	O
blocks	O
which	O
the	O
file	B-Application
system	I-Application
uses	O
to	O
segment	O
the	O
volume	O
is	O
also	O
stored	O
in	O
a	O
field	O
inside	O
the	O
primary	O
volume	O
descriptor	O
,	O
as	O
well	O
as	O
the	O
amount	O
of	O
space	O
occupied	O
by	O
the	O
volume	O
(	O
measured	O
in	O
number	O
of	O
logical	O
blocks	O
)	O
.	O
</s>
<s>
The	O
standard	O
specifies	O
that	O
ISO	B-General_Concept
2022	O
is	O
used	O
for	O
managing	O
code	O
sets	O
that	O
are	O
wider	O
than	O
8	O
bytes	O
,	O
and	O
that	O
ISO	B-General_Concept
2375	O
escape	O
sequences	O
are	O
used	O
to	O
identify	O
each	O
particular	O
code	O
page	O
used	O
.	O
</s>
<s>
Consequently	O
,	O
ISO	B-Application
9660	I-Application
supports	O
international	O
single-byte	O
and	O
multi-byte	O
character	O
sets	O
,	O
provided	O
they	O
fit	O
into	O
the	O
framework	O
of	O
the	O
referenced	O
standards	O
.	O
</s>
<s>
However	O
,	O
ISO	B-Application
9660	I-Application
does	O
not	O
specify	O
any	O
code	O
pages	O
that	O
are	O
guaranteed	O
to	O
be	O
supported	O
:	O
all	O
use	O
of	O
code	O
tables	O
other	O
than	O
those	O
defined	O
in	O
the	O
standard	O
itself	O
are	O
subject	O
to	O
agreement	O
between	O
the	O
originator	O
and	O
the	O
recipient	O
of	O
the	O
volume	O
.	O
</s>
<s>
Enhanced	O
volume	O
descriptors	O
were	O
introduced	O
in	O
ISO	B-Application
9660	I-Application
,	O
Amendment	O
1	O
.	O
</s>
<s>
For	O
each	O
directory	O
in	O
the	O
image	O
,	O
the	O
path	O
table	O
provides	O
the	O
directory	O
identifier	O
,	O
the	O
location	O
of	O
the	O
extent	B-Application
in	O
which	O
the	O
directory	O
is	O
recorded	O
,	O
the	O
length	O
of	O
any	O
extended	B-Application
attributes	I-Application
associated	O
with	O
the	O
directory	O
,	O
and	O
the	O
index	O
of	O
its	O
parent	O
directory	O
path	O
table	O
entry	O
.	O
</s>
<s>
Both	O
directories	O
and	O
files	B-Operating_System
are	O
stored	O
as	O
extents	B-Application
,	O
which	O
are	O
sequential	O
series	O
of	O
sectors	O
.	O
</s>
<s>
Files	B-Operating_System
and	O
directories	O
are	O
differentiated	O
only	O
by	O
a	O
file	O
attribute	O
that	O
indicates	O
its	O
nature	O
(	O
similar	O
to	O
Unix	B-Application
)	O
.	O
</s>
<s>
The	O
attributes	O
of	O
a	O
file	O
are	O
stored	O
in	O
the	O
directory	O
entry	O
that	O
describes	O
the	O
file	O
,	O
and	O
optionally	O
in	O
the	O
extended	B-Application
attribute	I-Application
record	O
.	O
</s>
<s>
However	O
,	O
a	O
file	O
can	O
also	O
be	O
located	O
through	O
the	O
path	O
table	O
provided	O
by	O
the	O
file	B-Application
system	I-Application
.	O
</s>
<s>
Files	B-Operating_System
may	O
contain	O
one	O
single	O
file	O
section	O
.	O
</s>
<s>
Level	O
2	O
:	O
Files	B-Operating_System
may	O
contain	O
one	O
single	O
file	O
section	O
.	O
</s>
<s>
Files	B-Operating_System
are	O
also	O
allowed	O
to	O
consist	O
of	O
multiple	O
non-contiguous	O
sections	O
(	O
with	O
some	O
restrictions	O
as	O
to	O
order	O
)	O
.	O
</s>
<s>
A	O
CD-ROM	B-Device
producer	O
may	O
choose	O
one	O
of	O
the	O
lower	O
Levels	O
of	O
Interchange	O
specified	O
in	O
chapter	O
10	O
of	O
the	O
standard	O
,	O
and	O
further	O
restrict	O
file	O
name	O
length	O
from	O
30	O
characters	O
to	O
only	O
8+3	O
in	O
file	O
identifiers	O
,	O
and	O
8	O
in	O
directory	O
identifiers	O
in	O
order	O
to	O
promote	O
interchangeability	O
with	O
implementations	O
that	O
do	O
not	O
implement	O
the	O
full	O
standard	O
.	O
</s>
<s>
All	O
numbers	O
in	O
ISO	B-Application
9660	I-Application
file	B-Application
systems	I-Application
except	O
the	O
single	O
byte	O
value	O
used	O
for	O
the	O
GMT	O
offset	O
are	O
unsigned	O
numbers	O
.	O
</s>
<s>
As	O
the	O
length	O
of	O
a	O
file	O
's	O
extent	B-Application
on	O
disc	O
is	O
stored	O
in	O
a	O
32	O
bit	O
value	O
,	O
it	O
allows	O
for	O
a	O
maximum	O
length	O
of	O
just	O
over	O
4.2GB	O
(	O
more	O
precisely	O
,	O
one	O
byte	O
less	O
than	O
4GiB	O
)	O
.	O
</s>
<s>
It	O
is	O
possible	O
to	O
circumvent	O
this	O
limitation	O
by	O
using	O
the	O
multi-extent	O
(	O
fragmentation	O
)	O
feature	O
of	O
ISO	B-Application
9660	I-Application
Level	O
3	O
to	O
create	O
ISO	B-Application
9660	I-Application
file	B-Application
systems	I-Application
and	O
single	O
files	B-Operating_System
up	O
to	O
8TB	O
.	O
</s>
<s>
With	O
this	O
,	O
files	B-Operating_System
larger	O
than	O
4GiB	O
can	O
be	O
split	O
up	O
into	O
multiple	O
extents	B-Application
(	O
sequential	O
series	O
of	O
sectors	O
)	O
,	O
each	O
not	O
exceeding	O
the	O
4	O
GiB	O
limit	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
free	O
software	O
such	O
as	O
InfraRecorder	B-Application
,	O
ImgBurn	B-Application
and	O
mkisofs	B-Language
as	O
well	O
as	O
Roxio	B-Operating_System
Toast	I-Operating_System
are	O
able	O
to	O
create	O
ISO	B-Application
9660	I-Application
file	B-Application
systems	I-Application
that	O
use	O
multi-extent	O
files	B-Operating_System
to	O
store	O
files	B-Operating_System
larger	O
than	O
4	O
GiB	O
on	O
appropriate	O
media	O
such	O
as	O
recordable	O
DVDs	O
.	O
</s>
<s>
Linux	B-Application
supports	O
multiple	O
extents	B-Application
.	O
</s>
<s>
There	O
are	O
several	O
extensions	O
to	O
ISO	B-Application
9660	I-Application
that	O
relax	O
some	O
of	O
its	O
limitations	O
.	O
</s>
<s>
Notable	O
examples	O
include	O
Rock	O
Ridge	O
(	O
Unix-style	B-Operating_System
permissions	O
and	O
longer	O
names	O
)	O
,	O
Joliet	O
(	O
Unicode	O
,	O
allowing	O
non-Latin	O
scripts	O
to	O
be	O
used	O
)	O
,	O
El	B-Device
Torito	I-Device
(	O
enables	O
CDs	O
to	O
be	O
bootable	B-Operating_System
)	O
and	O
the	O
Apple	O
ISO	B-Application
9660	I-Application
Extensions	O
(	O
file	O
characteristics	O
specific	O
to	O
the	O
classic	B-Application
Mac	I-Application
OS	I-Application
and	O
macOS	B-Application
,	O
such	O
as	O
resource	B-Operating_System
forks	I-Operating_System
,	O
file	O
backup	O
date	O
and	O
more	O
)	O
.	O
</s>
<s>
In	O
an	O
ISO	B-Application
9660	I-Application
volume	O
,	O
every	O
directory	O
entry	O
has	O
an	O
optional	O
system	O
use	O
area	O
whose	O
contents	O
are	O
undefined	O
and	O
left	O
to	O
be	O
interpreted	O
by	O
the	O
system	O
.	O
</s>
<s>
The	O
idea	O
behind	O
SUSP	O
was	O
that	O
it	O
would	O
enable	O
any	O
number	O
of	O
independent	O
extensions	O
to	O
ISO	B-Application
9660	I-Application
to	O
be	O
created	O
and	O
included	O
on	O
a	O
volume	O
without	O
conflicting	O
.	O
</s>
<s>
Transparently	O
decompressed	O
by	O
Linux	B-Application
kernel	O
if	O
built	O
with	O
CONFIG_ZISOFS	O
.	O
</s>
<s>
AL	O
:	O
records	O
Extended	B-Application
File	I-Application
Attributes	I-Application
,	O
including	O
ACLs	O
.	O
</s>
<s>
Proposed	O
by	O
libburnia	B-Application
,	O
supported	O
by	O
libisofs	O
.	O
</s>
<s>
The	O
Apple	O
extensions	O
do	O
not	O
technically	O
follow	O
the	O
SUSP	O
standard	O
;	O
however	O
the	O
basic	O
structure	O
of	O
the	O
AA	O
and	O
AB	O
fields	O
defined	O
by	O
Apple	O
are	O
forward	B-General_Concept
compatible	I-General_Concept
with	O
SUSP	O
;	O
so	O
that	O
,	O
with	O
care	O
,	O
a	O
volume	O
can	O
use	O
both	O
Apple	O
extensions	O
as	O
well	O
as	O
RRIP	O
extensions	O
.	O
</s>
<s>
The	O
Rock	O
Ridge	O
Interchange	O
Protocol	O
(	O
RRIP	O
,	O
IEEE	O
P1282	O
)	O
is	O
an	O
extension	O
which	O
adds	O
POSIX	O
file	B-Application
system	I-Application
semantics	O
.	O
</s>
<s>
The	O
availability	O
of	O
these	O
extension	O
properties	O
allows	O
for	O
better	O
integration	O
with	O
Unix	B-Application
and	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
.	O
</s>
<s>
Amiga	B-Device
Rock	O
Ridge	O
is	O
similar	O
to	O
RRIP	O
,	O
except	O
it	O
provides	O
additional	O
properties	O
used	O
by	O
AmigaOS	B-Application
.	O
</s>
<s>
Thus	O
both	O
Amiga	B-Device
Rock	O
Ridge	O
and	O
the	O
POSIX	O
RRIP	O
may	O
be	O
used	O
simultaneously	O
on	O
the	O
same	O
volume	O
.	O
</s>
<s>
Some	O
of	O
the	O
specific	O
properties	O
supported	O
by	O
this	O
extension	O
are	O
the	O
additional	O
Amiga-bits	O
for	O
files	B-Operating_System
.	O
</s>
<s>
The	O
first	O
publicly	O
available	O
software	O
to	O
master	O
a	O
CD-ROM	B-Device
with	O
Amiga	B-Device
extensions	O
was	O
MakeCD	O
,	O
an	O
Amiga	B-Device
software	O
which	O
Angela	O
Schmidt	O
developed	O
together	O
with	O
Patrick	O
Ohly	O
.	O
</s>
<s>
El	B-Device
Torito	I-Device
is	O
an	O
extension	O
designed	O
to	O
allow	O
booting	B-Operating_System
a	O
computer	O
from	O
a	O
CD-ROM	B-Device
.	O
</s>
<s>
According	O
to	O
legend	O
,	O
the	O
El	B-Device
Torito	I-Device
CD/DVD	O
extension	O
to	O
ISO	B-Application
9660	I-Application
got	O
its	O
name	O
because	O
its	O
design	O
originated	O
in	O
an	O
El	B-Device
Torito	I-Device
restaurant	O
in	O
Irvine	O
,	O
California	O
(	O
)	O
.	O
</s>
<s>
A	O
32-bit	O
PC	O
BIOS	O
will	O
search	O
for	O
boot	B-Operating_System
code	O
on	O
an	O
ISO	B-Application
9660	I-Application
CD-ROM	B-Device
.	O
</s>
<s>
The	O
standard	O
allows	O
for	O
booting	B-Operating_System
in	O
two	O
different	O
modes	O
.	O
</s>
<s>
Either	O
in	O
hard	B-Device
disk	I-Device
emulation	O
when	O
the	O
boot	B-Operating_System
information	O
can	O
be	O
accessed	O
directly	O
from	O
the	O
CD	O
media	O
,	O
or	O
in	O
floppy	B-Device
emulation	O
mode	O
where	O
the	O
boot	B-Operating_System
information	O
is	O
stored	O
in	O
an	O
image	B-Application
file	I-Application
of	O
a	O
floppy	B-Device
disk	I-Device
,	O
which	O
is	O
loaded	O
from	O
the	O
CD	O
and	O
then	O
behaves	O
as	O
a	O
virtual	O
floppy	B-Device
disk	I-Device
.	O
</s>
<s>
This	O
is	O
useful	O
for	O
computers	O
that	O
were	O
designed	O
to	O
boot	B-Operating_System
only	O
from	O
a	O
floppy	B-Device
drive	I-Device
.	O
</s>
<s>
The	O
drive	O
number	O
(	O
for	O
INT	B-Device
13H	I-Device
)	O
assigned	O
is	O
any	O
of	O
80hex	O
(	O
hard	B-Device
disk	I-Device
emulation	O
)	O
,	O
00hex	O
(	O
floppy	B-Device
disk	I-Device
emulation	O
)	O
or	O
an	O
arbitrary	O
number	O
if	O
the	O
BIOS	O
should	O
not	O
provide	O
emulation	O
.	O
</s>
<s>
Emulation	O
is	O
useful	O
for	O
booting	B-Operating_System
older	O
operating	B-General_Concept
systems	I-General_Concept
from	O
a	O
CD	O
,	O
by	O
making	O
it	O
appear	O
to	O
them	O
as	O
if	O
they	O
were	O
booted	O
from	O
a	O
hard	O
or	O
floppy	B-Device
disk	I-Device
.	O
</s>
<s>
El	B-Device
Torito	I-Device
can	O
also	O
be	O
used	O
to	O
produce	O
CDs	O
which	O
can	O
boot	B-Operating_System
up	I-Operating_System
Linux	B-Application
operating	I-Application
systems	I-Application
,	O
by	O
including	O
the	O
GRUB	B-Application
bootloader	O
on	O
the	O
CD	O
and	O
following	O
the	O
Multiboot	O
Specification	O
.	O
</s>
<s>
While	O
the	O
El	B-Device
Torito	I-Device
spec	O
alludes	O
to	O
a	O
"	O
Mac	O
"	O
platform	O
ID	O
,	O
PowerPC-based	O
Apple	O
Macintosh	O
computers	O
do	O
n't	O
use	O
it	O
.	O
</s>
<s>
Joliet	O
is	O
an	O
extension	O
specified	O
and	O
endorsed	O
by	O
Microsoft	O
and	O
has	O
been	O
supported	O
by	O
all	O
versions	O
of	O
its	O
Windows	B-Application
operating	I-Application
system	I-Application
since	O
Windows	B-Application
95	I-Application
and	O
Windows	B-Device
NT	I-Device
4.0	I-Device
.	O
</s>
<s>
Its	O
primary	O
focus	O
is	O
the	O
relaxation	O
of	O
the	O
filename	O
restrictions	O
inherent	O
with	O
full	O
ISO	B-Application
9660	I-Application
compliance	O
.	O
</s>
<s>
Joliet	O
accomplishes	O
this	O
by	O
supplying	O
an	O
additional	O
set	O
of	O
filenames	O
that	O
are	O
encoded	O
in	O
UCS-2BE	O
(	O
UTF-16BE	O
in	O
practice	O
since	O
Windows	B-Application
2000	I-Application
)	O
.	O
</s>
<s>
However	O
,	O
the	O
documentation	O
for	O
mkisofs	B-Language
states	O
filenames	O
up	O
to	O
103	O
characters	O
in	O
length	O
do	O
not	O
appear	O
to	O
cause	O
problems	O
.	O
</s>
<s>
Many	O
current	O
PC	O
operating	B-General_Concept
systems	I-General_Concept
are	O
able	O
to	O
read	O
Joliet-formatted	O
media	O
,	O
thus	O
allowing	O
exchange	O
of	O
files	B-Operating_System
between	O
those	O
operating	B-General_Concept
systems	I-General_Concept
even	O
if	O
non-Roman	O
characters	O
are	O
involved	O
(	O
such	O
as	O
Arabic	O
,	O
Japanese	O
or	O
Cyrillic	O
)	O
,	O
which	O
was	O
formerly	O
not	O
possible	O
with	O
plain	O
ISO	O
9660-formatted	O
media	O
.	O
</s>
<s>
Operating	B-General_Concept
systems	I-General_Concept
which	O
can	O
read	O
Joliet	O
media	O
include	O
:	O
</s>
<s>
Microsoft	B-Application
Windows	I-Application
;	O
Microsoft	O
recommends	O
the	O
use	O
of	O
the	O
Joliet	O
extension	O
for	O
developers	O
targeting	O
Windows	B-Application
.	O
</s>
<s>
However	O
,	O
Romeo	O
is	O
not	O
backwards	O
compatible	O
with	O
ISO	B-Application
9660	I-Application
and	O
discs	O
authored	O
using	O
this	O
file	B-Application
system	I-Application
can	O
only	O
be	O
read	O
under	O
the	O
Windows	B-Application
9x	O
and	O
Windows	B-Device
NT	I-Device
platforms	O
,	O
thus	O
not	O
allowing	O
exchange	O
of	O
files	B-Operating_System
between	O
those	O
operating	B-General_Concept
systems	I-General_Concept
if	O
non-Roman	O
characters	O
are	O
involved	O
(	O
such	O
as	O
Arabic	O
,	O
Japanese	O
or	O
Cyrillic	O
)	O
,	O
for	O
example	O
ü	O
becomes	O
³	O
.	O
</s>
<s>
Apple	O
Computer	O
authored	O
a	O
set	O
of	O
extensions	O
that	O
add	O
ProDOS	B-Operating_System
or	O
HFS/HFS	O
+	O
(	O
the	O
primary	O
contemporary	O
file	B-Application
systems	I-Application
for	O
the	O
classic	B-Application
Mac	I-Application
OS	I-Application
)	O
properties	O
to	O
the	O
filesystem	B-Application
.	O
</s>
<s>
In	O
order	O
to	O
allow	O
non-Macintosh	O
systems	O
to	O
access	O
Macintosh	O
files	B-Operating_System
on	O
CD-ROMs	B-Device
,	O
Apple	O
chose	O
to	O
use	O
an	O
extension	O
of	O
the	O
standard	O
ISO	B-Application
9660	I-Application
format	O
.	O
</s>
<s>
Most	O
of	O
the	O
data	O
,	O
other	O
than	O
the	O
Apple	O
specific	O
metadata	O
,	O
remains	O
visible	O
to	O
operating	B-General_Concept
systems	I-General_Concept
that	O
are	O
able	O
to	O
read	O
ISO	B-Application
9660	I-Application
.	O
</s>
<s>
For	O
operating	B-General_Concept
systems	I-General_Concept
which	O
do	O
not	O
support	O
any	O
extensions	O
,	O
a	O
name	O
translation	O
file	O
TRANS.TBL	O
must	O
be	O
used	O
.	O
</s>
<s>
The	O
TRANS.TBL	O
file	O
is	O
a	O
plain	O
ASCII	B-Protocol
text	I-Protocol
file	I-Protocol
.	O
</s>
<s>
Most	O
implementations	O
that	O
create	O
TRANS.TBL	O
files	B-Operating_System
put	O
a	O
single	O
space	O
between	O
the	O
file	O
type	O
and	O
ISO	B-Application
9660	I-Application
name	O
and	O
some	O
arbitrary	O
number	O
of	O
tabs	O
between	O
the	O
ISO	B-Application
9660	I-Application
filename	O
and	O
the	O
extended	O
filename	O
.	O
</s>
<s>
Native	O
support	O
for	O
using	O
TRANS.TBL	O
still	O
exists	O
in	O
many	O
ISO	B-Application
9660	I-Application
implementations	O
,	O
particularly	O
those	O
related	O
to	O
Unix	B-Application
.	O
</s>
<s>
However	O
,	O
it	O
has	O
long	O
since	O
been	O
superseded	O
by	O
other	O
extensions	O
,	O
and	O
modern	O
utilities	O
that	O
create	O
ISO	B-Application
9660	I-Application
images	I-Application
either	O
cannot	O
create	O
TRANS.TBL	O
files	B-Operating_System
at	O
all	O
,	O
or	O
no	O
longer	O
create	O
them	O
unless	O
explicitly	O
requested	O
by	O
the	O
user	O
.	O
</s>
<s>
Since	O
a	O
TRANS.TBL	O
file	O
has	O
no	O
special	O
identification	O
other	O
than	O
its	O
name	O
,	O
it	O
can	O
also	O
be	O
created	O
separately	O
and	O
included	O
in	O
the	O
directory	O
before	O
filesystem	B-Application
creation	O
.	O
</s>
<s>
The	O
ISO	B-General_Concept
13490	O
standard	O
is	O
an	O
extension	O
to	O
the	O
ISO	B-Application
9660	I-Application
format	O
that	O
adds	O
support	O
for	O
multiple	O
sessions	O
on	O
a	O
disc	O
.	O
</s>
<s>
Since	O
ISO	B-Application
9660	I-Application
is	O
by	O
design	O
a	O
read-only	O
,	O
pre-mastered	O
file	B-Application
system	I-Application
,	O
all	O
the	O
data	O
has	O
to	O
be	O
written	O
in	O
one	O
go	O
or	O
"	O
session	O
"	O
to	O
the	O
medium	O
.	O
</s>
<s>
ISO	B-General_Concept
13490	O
was	O
created	O
to	O
allow	O
adding	O
more	O
files	B-Operating_System
to	O
a	O
writeable	O
disc	O
such	O
as	O
CD-R	O
in	O
multiple	O
sessions	O
.	O
</s>
<s>
JIS	B-Application
X	I-Application
0606:1998	I-Application
,	O
also	O
known	O
as	O
ISO	O
9660:1999	O
,	O
is	O
a	O
Japanese	O
Industrial	O
Standard	O
draft	O
created	O
by	O
the	O
Japanese	O
National	O
Body	O
(	O
JTC1	O
N4222	O
)	O
in	O
order	O
to	O
make	O
some	O
improvements	O
and	O
remove	O
some	O
limitations	O
from	O
the	O
original	O
ISO	B-Application
9660	I-Application
standard	O
.	O
</s>
<s>
This	O
draft	O
was	O
submitted	O
in	O
1998	O
,	O
but	O
it	O
has	O
not	O
been	O
ratified	O
as	O
an	O
ISO	B-General_Concept
standard	O
yet	O
.	O
</s>
<s>
Some	O
operating	B-General_Concept
systems	I-General_Concept
allow	O
these	O
relaxations	O
as	O
well	O
when	O
reading	O
optical	O
discs	O
.	O
</s>
<s>
Several	O
disc	O
authoring	O
tools	O
(	O
such	O
as	O
Nero	B-Application
Burning	I-Application
ROM	I-Application
,	O
mkisofs	B-Language
and	O
ImgBurn	B-Application
)	O
support	O
a	O
so-called	O
"	O
ISO	O
9660:1999	O
"	O
mode	O
(	O
sometimes	O
called	O
"	O
ISO	B-Application
9660	I-Application
v2	O
"	O
or	O
"	O
ISO	B-Application
9660	I-Application
Level	O
4	O
"	O
mode	O
)	O
that	O
removes	O
restrictions	O
following	O
the	O
guidelines	O
in	O
the	O
ISO	O
9660:1999	O
draft	O
.	O
</s>
<s>
The	O
ISO	B-General_Concept
13346/ECMA	O
-167	O
standard	O
was	O
designed	O
in	O
conjunction	O
to	O
the	O
ISO	B-General_Concept
13490	O
standard	O
.	O
</s>
<s>
This	O
new	O
format	O
addresses	O
most	O
of	O
the	O
shortcomings	O
of	O
ISO	B-Application
9660	I-Application
,	O
and	O
a	O
subset	O
of	O
it	O
evolved	O
into	O
the	O
Universal	O
Disk	O
Format	O
(	O
UDF	O
)	O
,	O
which	O
was	O
adopted	O
for	O
DVDs	O
.	O
</s>
<s>
The	O
volume	O
descriptor	O
table	O
retains	O
the	O
ISO9660	B-Application
layout	O
,	O
but	O
the	O
identifier	O
has	O
been	O
updated	O
.	O
</s>
<s>
Optical	B-General_Concept
disc	I-General_Concept
images	I-General_Concept
are	O
a	O
common	O
way	O
to	O
electronically	O
transfer	O
the	O
contents	O
of	O
CD-ROMs	B-Device
.	O
</s>
<s>
They	O
often	O
have	O
the	O
filename	O
extension	O
.iso	B-General_Concept
(	O
.iso9660	O
is	O
less	O
common	O
,	O
but	O
also	O
in	O
use	O
)	O
and	O
are	O
commonly	O
referred	O
to	O
as	O
"	O
ISOs	B-General_Concept
"	O
.	O
</s>
<s>
Most	O
operating	B-General_Concept
systems	I-General_Concept
support	O
reading	O
of	O
ISO	B-Application
9660	I-Application
formatted	O
discs	O
,	O
and	O
most	O
new	O
versions	O
support	O
the	O
extensions	O
such	O
as	O
Rock	O
Ridge	O
and	O
Joliet	O
.	O
</s>
<s>
Operating	B-General_Concept
systems	I-General_Concept
that	O
do	O
not	O
support	O
the	O
extensions	O
usually	O
show	O
the	O
basic	O
(	O
non-extended	O
)	O
features	O
of	O
a	O
plain	O
ISO	B-Application
9660	I-Application
disc	O
.	O
</s>
<s>
Operating	B-General_Concept
systems	I-General_Concept
that	O
support	O
ISO	B-Application
9660	I-Application
and	O
its	O
extensions	O
include	O
the	O
following	O
:	O
</s>
<s>
Microsoft	B-Device
Windows	I-Device
NT	I-Device
4.0	I-Device
,	O
Windows	B-Application
2000	I-Application
,	O
Windows	B-Application
XP	I-Application
,	O
and	O
newer	O
Windows	B-Application
versions	O
,	O
can	O
read	O
ISO	B-Application
9660	I-Application
Level	O
1	O
,	O
2	O
,	O
3	O
,	O
Joliet	O
,	O
and	O
ISO	O
9660:1999	O
.	O
</s>
<s>
Windows	B-Device
7	I-Device
may	O
also	O
mistake	O
UDF	O
format	O
for	O
CDFS	O
.	O
</s>
<s>
Apple	B-Application
GS/OS	I-Application
:	O
ISO	B-General_Concept
Level	O
1	O
and	O
2	O
support	O
via	O
the	O
HS.FST	O
File	B-Application
System	I-Application
Translator	O
.	O
</s>
<s>
Classic	B-Application
Mac	I-Application
OS	I-Application
7	O
to	O
9	O
:	O
ISO	B-General_Concept
Level	O
1	O
,	O
2	O
.	O
</s>
<s>
Optional	O
free	O
software	O
supports	O
Rock	O
Ridge	O
and	O
Joliet	O
(	O
including	O
ISO	B-General_Concept
Level	O
3	O
)	O
:	O
and	O
.	O
</s>
<s>
macOS	B-Application
(	O
all	O
versions	O
)	O
:	O
ISO	B-General_Concept
Level	O
1	O
,	O
2	O
,	O
Joliet	O
and	O
Rock	O
Ridge	O
Extensions	O
.	O
</s>
<s>
RISC	B-Operating_System
OS	I-Operating_System
support	O
for	O
optical	O
media	O
written	O
on	O
a	O
PC	O
is	O
patchy	O
.	O
</s>
