<s>
A	O
media	B-Application
type	I-Application
(	O
formerly	O
known	O
as	O
a	O
MIME	B-Application
type	I-Application
)	O
is	O
a	O
two-part	O
identifier	O
for	O
file	O
formats	O
and	O
format	O
contents	O
transmitted	O
on	O
the	O
Internet	O
.	O
</s>
<s>
Media	B-Application
types	I-Application
were	O
originally	O
defined	O
in	O
Request	O
for	O
Comments	O
(	O
MIME	B-Protocol
)	O
Part	O
One	O
:	O
Format	O
of	O
Internet	O
Message	O
Bodies	O
(	O
Nov	O
1996	O
)	O
in	O
November	O
1996	O
as	O
a	O
part	O
of	O
the	O
MIME	B-Protocol
(	O
Multipurpose	B-Protocol
Internet	I-Protocol
Mail	I-Protocol
Extensions	I-Protocol
)	O
specification	O
,	O
for	O
denoting	O
type	O
of	O
email	O
message	O
content	O
and	O
attachments	O
;	O
hence	O
the	O
original	O
name	O
,	O
MIME	B-Application
type	I-Application
.	O
</s>
<s>
Media	B-Application
types	I-Application
are	O
also	O
used	O
by	O
other	O
internet	O
protocols	O
such	O
as	O
HTTP	B-Protocol
and	O
document	O
file	O
formats	O
such	O
as	O
HTML	B-General_Concept
,	O
for	O
similar	O
purposes	O
.	O
</s>
<s>
A	O
media	B-Application
type	I-Application
consists	O
of	O
a	O
type	O
and	O
a	O
subtype	O
,	O
which	O
is	O
further	O
structured	O
into	O
a	O
tree	O
.	O
</s>
<s>
A	O
media	B-Application
type	I-Application
can	O
optionally	O
define	O
a	O
suffix	O
and	O
parameters	O
:	O
</s>
<s>
As	O
an	O
example	O
,	O
an	O
HTML	B-General_Concept
file	O
might	O
be	O
designated	O
.	O
</s>
<s>
The	O
"	O
type	O
"	O
part	O
defines	O
the	O
broad	O
use	O
of	O
the	O
media	B-Application
type	I-Application
.	O
</s>
<s>
All	O
media	B-Application
types	I-Application
should	O
be	O
registered	O
using	O
the	O
IANA	O
registration	O
procedures	O
.	O
</s>
<s>
For	O
the	O
efficiency	O
and	O
flexibility	O
of	O
the	O
media	B-Application
type	I-Application
registration	O
process	O
,	O
different	O
structures	O
of	O
subtypes	O
can	O
be	O
registered	O
in	O
registration	O
trees	O
that	O
are	O
distinguished	O
by	O
the	O
use	O
of	O
tree	O
prefixes	O
.	O
</s>
<s>
The	O
vendor	O
tree	O
includes	O
media	B-Application
types	I-Application
associated	O
with	O
publicly	O
available	O
products	O
.	O
</s>
<s>
Industry	O
consortia	O
as	O
well	O
as	O
non-commercial	O
entities	O
can	O
register	O
media	B-Application
types	I-Application
in	O
the	O
vendor	O
tree	O
.	O
</s>
<s>
The	O
personal	O
or	O
vanity	O
tree	O
includes	O
media	B-Application
types	I-Application
associated	O
with	O
non	O
publicly	O
available	O
products	O
or	O
experimental	O
media	B-Application
types	I-Application
.	O
</s>
<s>
The	O
unregistered	O
tree	O
includes	O
media	B-Application
types	I-Application
intended	O
exclusively	O
for	O
use	O
in	O
private	O
environments	O
and	O
only	O
with	O
the	O
active	O
agreement	O
of	O
the	O
parties	O
exchanging	O
them	O
.	O
</s>
<s>
Media	B-Application
types	I-Application
in	O
this	O
tree	O
cannot	O
be	O
registered	O
.	O
</s>
<s>
Media	B-Application
types	I-Application
that	O
have	O
been	O
widely	O
deployed	O
(	O
with	O
a	O
subtype	O
prefixed	O
with	O
or	O
)	O
without	O
being	O
registered	O
,	O
should	O
be	O
,	O
if	O
possible	O
,	O
re-registered	O
with	O
a	O
proper	O
prefixed	O
subtype	O
.	O
</s>
<s>
If	O
this	O
is	O
not	O
possible	O
,	O
the	O
media	B-Application
type	I-Application
can	O
,	O
after	O
an	O
approval	O
by	O
both	O
the	O
media	B-Application
types	I-Application
reviewer	O
and	O
the	O
IESG	O
,	O
be	O
registered	O
in	O
the	O
standards	O
tree	O
with	O
its	O
unprefixed	O
subtype	O
.	O
</s>
<s>
Suffix	O
is	O
an	O
augmentation	O
to	O
the	O
media	B-Application
type	I-Application
definition	O
to	O
additionally	O
specify	O
the	O
underlying	O
structure	O
of	O
that	O
media	B-Application
type	I-Application
,	O
allowing	O
for	O
generic	O
processing	O
based	O
on	O
that	O
structure	O
and	O
independent	O
of	O
the	O
exact	O
type	O
's	O
particular	O
semantics	O
.	O
</s>
<s>
Media	B-Application
types	I-Application
that	O
make	O
use	O
of	O
a	O
named	O
structured	O
syntax	O
should	O
use	O
the	O
appropriate	O
IANA	O
registered	O
for	O
that	O
structured	O
syntax	O
when	O
they	O
are	O
registered	O
.	O
</s>
<s>
Mailcap	B-Application
(	O
derived	O
from	O
the	O
phrase	O
"	O
mail	O
capability	O
"	O
)	O
is	O
a	O
type	O
of	O
meta	O
file	O
used	O
to	O
configure	O
how	O
MIME-aware	O
applications	O
such	O
as	O
mail	O
clients	O
and	O
web	O
browsers	O
render	O
files	O
of	O
different	O
MIME-types	B-Application
.	O
</s>
<s>
The	O
mailcap	B-Application
format	O
is	O
defined	O
by	O
RFC	O
1524	O
"	O
A	O
User	O
Agent	O
Configuration	O
Mechanism	O
for	O
Multimedia	O
Mail	O
Format	O
Information	O
"	O
but	O
is	O
not	O
defined	O
as	O
an	O
Internet	O
standard	O
.	O
</s>
<s>
Lines	O
can	O
be	O
comments	O
starting	O
with	O
the	O
#	O
character	O
,	O
or	O
a	O
mime-type	B-Application
followed	O
by	O
how	O
to	O
handle	O
that	O
mime	B-Application
type	I-Application
.	O
</s>
<s>
An	O
associated	O
file	O
is	O
the	O
mime.types	O
file	O
,	O
which	O
associates	O
filename	O
extensions	O
with	O
a	O
MIME	B-Application
type	I-Application
.	O
</s>
<s>
If	O
the	O
MIME	B-Application
type	I-Application
is	O
properly	O
set	O
,	O
this	O
is	O
unnecessary	O
,	O
but	O
MIME	B-Application
types	I-Application
may	O
be	O
incorrectly	O
set	O
,	O
or	O
set	O
to	O
a	O
generic	O
type	O
such	O
as	O
,	O
and	O
mime.types	O
allows	O
one	O
to	O
fall	O
back	O
on	O
the	O
extension	O
in	O
these	O
cases	O
.	O
</s>
<s>
Similarly	O
,	O
since	O
many	O
file	O
systems	O
do	O
not	O
store	O
MIME	B-Application
type	I-Application
information	O
,	O
but	O
instead	O
rely	O
on	O
the	O
filename	O
extension	O
,	O
a	O
mime.types	O
file	O
is	O
frequently	O
used	O
by	O
web	O
servers	O
to	O
determine	O
MIME	B-Application
type	I-Application
.	O
</s>
<s>
When	O
viewing	O
a	O
file	O
,	O
these	O
two	O
work	O
together	O
as	O
follows	O
:	O
associates	O
an	O
extension	O
with	O
a	O
MIME	B-Application
type	I-Application
,	O
while	O
mailcap	B-Application
associates	O
a	O
MIME	B-Application
type	I-Application
with	O
a	O
program	O
.	O
</s>
<s>
In	O
UNIX-type	O
systems	O
,	O
the	O
mime.types	O
file	O
is	O
usually	O
located	O
at	O
/etc/mime.types	O
and/or	O
$	O
HOME/.mime.types	O
and	O
the	O
format	O
is	O
simply	O
that	O
each	O
line	O
is	O
a	O
space-delimited	O
list	O
of	O
a	O
MIME	B-Application
type	I-Application
,	O
followed	O
by	O
zero	O
or	O
more	O
extensions	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
HTML	B-Application
type	I-Application
can	O
be	O
associated	O
with	O
the	O
extensions	O
and	O
by	O
the	O
following	O
line	O
:	O
</s>
<s>
The	O
mime.types	O
file	O
dates	O
to	O
Netscape	B-Protocol
,	O
where	O
it	O
used	O
a	O
different	O
format	O
;	O
it	O
used	O
key	B-Application
–	I-Application
value	I-Application
pairs	I-Application
and	O
a	O
comma-separated	O
list	O
of	O
extensions	O
,	O
together	O
with	O
a	O
standard	O
header	O
consisting	O
of	O
a	O
specific	O
comment	O
that	O
identifies	O
the	O
file	O
as	O
a	O
mime.types	O
file	O
,	O
as	O
follows	O
.	O
</s>
