<s>
The	O
Blue	B-Application
Book	I-Application
is	O
a	O
compact	O
disc	O
standard	O
developed	O
in	O
1995	O
by	O
Philips	O
and	O
Sony	O
.	O
</s>
<s>
It	O
defines	O
the	O
Enhanced	B-Application
Music	I-Application
CD	I-Application
format	O
(	O
E-CD	O
,	O
also	O
known	O
as	O
CD-Extra	O
,	O
CD-Plus	O
and	O
CD+	O
)	O
,	O
which	O
combines	O
audio	O
tracks	O
and	O
data	B-Device
tracks	I-Device
on	O
the	O
same	O
disc	O
.	O
</s>
<s>
The	O
second	O
session	O
contains	O
CD-ROM	B-Device
data	O
files	O
with	O
content	O
often	O
related	O
to	O
the	O
audio	O
tracks	O
in	O
the	O
first	O
session	O
.	O
</s>
<s>
The	O
second	O
session	O
will	O
only	O
be	O
used	O
by	O
computer	O
systems	O
equipped	O
with	O
a	O
CD-ROM	B-Device
drive	O
,	O
or	O
by	O
special	O
“	O
Enhanced	O
CD	O
players	O
”	O
.	O
</s>
<s>
The	O
second	O
session	O
of	O
a	O
E-CD	O
contains	O
one	O
track	O
in	O
CD-ROM	B-Device
XA	O
Mode	O
2	O
,	O
Form	O
1	O
format	O
.	O
</s>
<s>
It	O
must	O
contain	O
certain	O
specific	O
files	O
inside	O
an	O
ISO	B-Application
9660	I-Application
file	B-Application
system	I-Application
,	O
though	O
an	O
HFS	B-Application
file	B-Application
system	I-Application
may	O
also	O
be	O
included	O
for	O
compatibility	O
with	O
the	O
classic	B-Application
Mac	I-Application
OS	I-Application
.	O
</s>
<s>
The	O
mandatory	O
files	O
and	O
directories	O
include	O
an	O
autorun.inf	B-Protocol
file	O
compatible	O
with	O
the	O
Windows	B-Application
95	I-Application
AutoRun	O
feature	O
;	O
a	O
CDPLUS	O
and	O
a	O
PICTURES	O
directories	O
;	O
and	O
an	O
optional	O
DATA	O
directory	O
.	O
</s>
<s>
There	O
were	O
other	O
technologies	O
that	O
solved	O
the	O
same	O
problem	O
,	O
but	O
they	O
were	O
not	O
compatible	O
with	O
many	O
existing	O
CD	O
players	O
and	O
so	O
this	O
approach	O
was	O
brought	O
to	O
Sony	O
and	O
Philips	O
where	O
it	O
was	O
written	O
into	O
the	O
Blue	B-Application
Book	I-Application
standard	O
.	O
</s>
<s>
The	O
term	O
"	O
enhanced	O
CD	O
"	O
is	O
also	O
an	O
umbrella	O
term	O
and	O
a	O
certification	O
mark	O
used	O
to	O
refer	O
to	O
different	O
CD	O
formats	O
that	O
support	O
audio	O
and	O
data	O
content	O
,	O
including	O
mixed	O
mode	O
CDs	O
,	O
CD-i	B-Device
and	O
CD-i	B-Device
Ready	O
.	O
</s>
