<s>
The	O
Windows	B-Protocol
Registry	I-Protocol
is	O
a	O
hierarchical	B-General_Concept
database	I-General_Concept
that	O
stores	O
low-level	O
settings	O
for	O
the	O
Microsoft	B-Application
Windows	I-Application
operating	I-Application
system	I-Application
and	O
for	O
applications	O
that	O
opt	O
to	O
use	O
the	O
registry	O
.	O
</s>
<s>
The	O
kernel	B-Operating_System
,	O
device	B-Application
drivers	I-Application
,	O
services	O
,	O
Security	O
Accounts	O
Manager	O
,	O
and	O
user	B-Application
interfaces	I-Application
can	O
all	O
use	O
the	O
registry	O
.	O
</s>
<s>
The	O
registry	O
also	O
allows	O
access	O
to	O
counters	B-Application
for	O
profiling	O
system	O
performance	O
.	O
</s>
<s>
In	O
other	O
words	O
,	O
the	O
registry	O
or	O
Windows	B-Protocol
Registry	I-Protocol
contains	O
information	O
,	O
settings	O
,	O
options	O
,	O
and	O
other	O
values	O
for	O
programs	O
and	O
hardware	O
installed	O
on	O
all	O
versions	O
of	O
Microsoft	B-Application
Windows	I-Application
operating	I-Application
systems	I-Application
.	O
</s>
<s>
For	O
example	O
,	O
when	O
a	O
program	O
is	O
installed	O
,	O
a	O
new	O
subkey	O
containing	O
settings	O
such	O
as	O
a	O
program	O
's	O
location	O
,	O
its	O
version	O
,	O
and	O
how	O
to	O
start	O
the	O
program	O
,	O
are	O
all	O
added	O
to	O
the	O
Windows	B-Protocol
Registry	I-Protocol
.	O
</s>
<s>
When	O
introduced	O
with	O
Windows	B-Application
3.1	I-Application
,	O
the	O
Windows	B-Protocol
Registry	I-Protocol
primarily	O
stored	O
configuration	O
information	O
for	O
COM-based	O
components	O
.	O
</s>
<s>
Windows	B-Application
95	I-Application
and	O
Windows	B-Device
NT	I-Device
extended	O
its	O
use	O
to	O
rationalize	O
and	O
centralize	O
the	O
information	O
in	O
the	O
profusion	O
of	O
INI	B-Protocol
files	I-Protocol
,	O
which	O
held	O
the	O
configurations	O
for	O
individual	O
programs	O
,	O
and	O
were	O
stored	O
at	O
various	O
locations	O
.	O
</s>
<s>
It	O
is	O
not	O
a	O
requirement	O
for	O
Windows	B-Application
applications	I-Application
to	O
use	O
the	O
Windows	B-Protocol
Registry	I-Protocol
.	O
</s>
<s>
For	O
example	O
,	O
.NET	B-Application
Framework	I-Application
applications	O
use	O
XML	B-Protocol
files	O
for	O
configuration	O
,	O
while	O
portable	B-Application
applications	I-Application
usually	O
keep	O
their	O
configuration	O
files	O
with	O
their	O
executables	B-Application
.	O
</s>
<s>
Prior	O
to	O
the	O
Windows	B-Protocol
Registry	I-Protocol
,	O
.INI	B-Protocol
files	O
stored	O
each	O
program	O
's	O
settings	O
as	O
a	O
text	B-General_Concept
file	I-General_Concept
or	O
binary	O
file	O
,	O
often	O
located	O
in	O
a	O
shared	O
location	O
that	O
did	O
not	O
provide	O
user-specific	O
settings	O
in	O
a	O
multi-user	O
scenario	O
.	O
</s>
<s>
By	O
contrast	O
,	O
the	O
Windows	B-Protocol
Registry	I-Protocol
stores	O
all	O
application	O
settings	O
in	O
one	O
logical	O
repository	O
(	O
but	O
a	O
number	O
of	O
discrete	O
files	O
)	O
and	O
in	O
a	O
standardized	O
form	O
.	O
</s>
<s>
According	O
to	O
Microsoft	O
,	O
this	O
offers	O
several	O
advantages	O
over	O
.INI	B-Protocol
files	O
.	O
</s>
<s>
Since	O
file	O
parsing	O
is	O
done	O
much	O
more	O
efficiently	O
with	O
a	O
binary	O
format	O
,	O
it	O
may	O
be	O
read	O
from	O
or	O
written	O
to	O
more	O
quickly	O
than	O
a	O
text	O
INI	B-Protocol
file	I-Protocol
.	O
</s>
<s>
Furthermore	O
,	O
strongly	O
typed	O
data	O
can	O
be	O
stored	O
in	O
the	O
registry	O
,	O
as	O
opposed	O
to	O
the	O
text	O
information	O
stored	O
in	O
.INI	B-Protocol
files	O
.	O
</s>
<s>
This	O
is	O
a	O
benefit	O
when	O
editing	O
keys	O
manually	O
using	O
regedit.exe	B-Protocol
,	O
the	O
built-in	O
Windows	B-Protocol
Registry	I-Protocol
Editor	O
.	O
</s>
<s>
Backup	O
and	O
restoration	O
is	O
also	O
simplified	O
as	O
the	O
registry	O
can	O
be	O
accessed	O
over	O
a	O
network	O
connection	O
for	O
remote	O
management/support	O
,	O
including	O
from	O
scripts	O
,	O
using	O
the	O
standard	O
set	O
of	O
APIs	B-Application
,	O
as	O
long	O
as	O
the	O
Remote	B-Protocol
Registry	I-Protocol
service	O
is	O
running	O
and	O
firewall	O
rules	O
permit	O
this	O
.	O
</s>
<s>
Because	O
the	O
registry	O
is	O
a	O
database	O
,	O
it	O
offers	O
improved	O
system	O
integrity	O
with	O
features	O
such	O
as	O
atomic	B-General_Concept
updates	I-General_Concept
.	O
</s>
<s>
Where	O
changes	O
are	O
made	O
to	O
.INI	B-Protocol
files	O
,	O
such	O
race	B-Operating_System
conditions	I-Operating_System
can	O
result	O
in	O
inconsistent	O
data	O
that	O
does	O
not	O
match	O
either	O
attempted	O
update	O
.	O
</s>
<s>
Windows	B-Application
Vista	I-Application
and	O
later	O
operating	O
systems	O
provide	O
transactional	O
updates	O
to	O
the	O
registry	O
by	O
means	O
of	O
the	O
Kernel	B-Operating_System
Transaction	O
Manager	O
,	O
extending	O
the	O
atomicity	B-General_Concept
guarantees	O
across	O
multiple	O
key	O
and/or	O
value	O
changes	O
,	O
with	O
traditional	O
commit	O
–	O
abort	O
semantics	O
.	O
</s>
<s>
(	O
Note	O
however	O
that	O
NTFS	B-Application
provides	O
such	O
support	O
for	O
the	O
file	O
system	O
as	O
well	O
,	O
so	O
the	O
same	O
guarantees	O
could	O
,	O
in	O
theory	O
,	O
be	O
obtained	O
with	O
traditional	O
configuration	O
files	O
.	O
)	O
</s>
<s>
Registry	B-Protocol
keys	I-Protocol
are	O
container	O
objects	O
similar	O
to	O
folders	O
.	O
</s>
<s>
The	O
hierarchy	O
of	O
registry	B-Protocol
keys	I-Protocol
can	O
only	O
be	O
accessed	O
from	O
a	O
known	O
root	O
key	O
handle	O
(	O
which	O
is	O
anonymous	O
but	O
whose	O
effective	O
value	O
is	O
a	O
constant	O
numeric	O
handle	O
)	O
that	O
is	O
mapped	O
to	O
the	O
content	O
of	O
a	O
registry	B-Protocol
key	I-Protocol
preloaded	O
by	O
the	O
kernel	B-Operating_System
from	O
a	O
stored	O
"	O
hive	O
"	O
,	O
or	O
to	O
the	O
content	O
of	O
a	O
subkey	O
within	O
another	O
root	O
key	O
,	O
or	O
mapped	O
to	O
a	O
registered	O
service	O
or	O
DLL	O
that	O
provides	O
access	O
to	O
its	O
contained	O
subkeys	O
and	O
values	O
.	O
</s>
<s>
There	O
are	O
seven	O
predefined	O
root	O
keys	O
,	O
traditionally	O
named	O
according	O
to	O
their	O
constant	O
handles	O
defined	O
in	O
the	O
Win32	B-Library
API	I-Library
,	O
or	O
by	O
synonymous	O
abbreviations	O
(	O
depending	O
on	O
applications	O
)	O
:	O
</s>
<s>
Like	O
other	O
files	O
and	O
services	O
in	O
Windows	O
,	O
all	O
registry	B-Protocol
keys	I-Protocol
may	O
be	O
restricted	O
by	O
access	O
control	O
lists	O
(	O
ACLs	O
)	O
,	O
depending	O
on	O
user	O
privileges	O
,	O
or	O
on	O
security	O
tokens	O
acquired	O
by	O
applications	O
,	O
or	O
on	O
system	O
security	O
policies	O
enforced	O
by	O
the	O
system	O
(	O
these	O
restrictions	O
may	O
be	O
predefined	O
by	O
the	O
system	O
itself	O
,	O
and	O
configured	O
by	O
local	O
system	O
administrators	O
or	O
by	O
domain	B-General_Concept
administrators	O
)	O
.	O
</s>
<s>
Registry	O
values	O
are	O
referenced	O
separately	O
from	O
registry	B-Protocol
keys	I-Protocol
.	O
</s>
<s>
Each	O
registry	O
value	O
stored	O
in	O
a	O
registry	B-Protocol
key	I-Protocol
has	O
a	O
unique	O
name	O
whose	O
letter	O
case	O
is	O
not	O
significant	O
.	O
</s>
<s>
The	O
Windows	B-Library
API	I-Library
functions	O
that	O
query	O
and	O
manipulate	O
registry	O
values	O
take	O
value	O
names	O
separately	O
from	O
the	O
key	O
path	O
and/or	O
handle	O
that	O
identifies	O
the	O
parent	O
key	O
.	O
</s>
<s>
Registry	O
values	O
may	O
contain	O
backslashes	O
in	O
their	O
names	O
,	O
but	O
doing	O
so	O
makes	O
them	O
difficult	O
to	O
distinguish	O
from	O
their	O
key	O
paths	O
when	O
using	O
some	O
legacy	O
Windows	B-Protocol
Registry	I-Protocol
API	B-Application
functions	I-Application
(	O
whose	O
usage	O
is	O
deprecated	O
in	O
Win32	B-Library
)	O
.	O
</s>
<s>
The	O
terminology	O
is	O
somewhat	O
misleading	O
,	O
as	O
each	O
registry	B-Protocol
key	I-Protocol
is	O
similar	O
to	O
an	O
associative	B-Application
array	I-Application
,	O
where	O
standard	O
terminology	O
would	O
refer	O
to	O
the	O
name	O
part	O
of	O
each	O
registry	O
value	O
as	O
a	O
"	O
key	O
"	O
.	O
</s>
<s>
The	O
terms	O
are	O
a	O
holdout	O
from	O
the	O
16-bit	B-Device
registry	O
in	O
Windows	O
3	O
,	O
in	O
which	O
registry	B-Protocol
keys	I-Protocol
could	O
not	O
contain	O
arbitrary	O
name/data	O
pairs	O
,	O
but	O
rather	O
contained	O
only	O
one	O
unnamed	O
value	O
(	O
which	O
had	O
to	O
be	O
a	O
string	O
)	O
.	O
</s>
<s>
In	O
this	O
sense	O
,	O
the	O
Windows	O
3	O
registry	O
was	O
like	O
a	O
single	O
associative	B-Application
array	I-Application
,	O
in	O
which	O
the	O
keys	O
(	O
in	O
the	O
sense	O
of	O
both	O
'	O
registry	B-Protocol
key	I-Protocol
 '	O
and	O
'	O
associative	B-Application
array	I-Application
key	O
 '	O
)	O
formed	O
a	O
hierarchy	O
,	O
and	O
the	O
registry	O
values	O
were	O
all	O
strings	O
.	O
</s>
<s>
For	O
compatibility	O
with	O
the	O
previous	O
behavior	O
,	O
each	O
registry	B-Protocol
key	I-Protocol
may	O
have	O
a	O
"	O
default	O
"	O
value	O
,	O
whose	O
name	O
is	O
the	O
empty	O
string	O
.	O
</s>
<s>
+	O
List	O
of	O
standard	O
registry	O
value	O
types	O
Type	O
ID	O
Symbolic	O
type	O
name	O
Meaning	O
and	O
encoding	O
of	O
the	O
data	O
stored	O
in	O
the	O
registry	O
value	O
0	O
REG_NONE	O
No	O
type	O
(	O
the	O
stored	O
value	O
,	O
if	O
any	O
)	O
1	O
REG_SZ	O
A	O
string	O
value	O
,	O
normally	O
stored	O
and	O
exposed	O
in	O
UTF-16LE	O
(	O
when	O
using	O
the	O
Unicode	O
version	O
of	O
Win32	B-Library
API	I-Library
functions	O
)	O
,	O
usually	O
terminated	O
by	O
a	O
NUL	O
character	O
2	O
REG_EXPAND_SZ	O
An	O
"	O
expandable	O
"	O
string	O
value	O
that	O
can	O
contain	O
environment	O
variables	O
,	O
normally	O
stored	O
and	O
exposed	O
in	O
UTF-16LE	O
,	O
usually	O
terminated	O
by	O
a	O
NUL	O
character	O
3	O
REG_BINARY	O
Binary	O
data	O
(	O
any	O
arbitrary	O
data	O
)	O
4	O
REG_DWORD	O
/	O
REG_DWORD_LITTLE_ENDIAN	O
A	O
DWORD	O
value	O
,	O
a	O
32-bit	O
unsigned	B-Algorithm
integer	O
(	O
numbers	O
between	O
0	O
and	O
4,294,967,295	O
[	O
232	O
–	O
1 ]	O
)	O
(	O
little-endian	O
)	O
5	O
REG_DWORD_BIG_ENDIAN	O
A	O
DWORD	O
value	O
,	O
a	O
32-bit	O
unsigned	B-Algorithm
integer	O
(	O
numbers	O
between	O
0	O
and	O
4,294,967,295	O
[	O
232	O
–	O
1 ]	O
)	O
(	O
big-endian	O
)	O
6	O
REG_LINK	O
A	O
symbolic	O
link	O
(	O
UNICODE	O
)	O
to	O
another	O
registry	B-Protocol
key	I-Protocol
,	O
specifying	O
a	O
root	O
key	O
and	O
the	O
path	O
to	O
the	O
target	O
key	O
7	O
REG_MULTI_SZ	O
A	O
multi-string	O
value	O
,	O
which	O
is	O
an	O
ordered	O
list	O
of	O
non-empty	O
strings	O
,	O
normally	O
stored	O
and	O
exposed	O
in	O
Unicode	O
,	O
each	O
one	O
terminated	O
by	O
a	O
null	O
character	O
,	O
the	O
list	O
being	O
normally	O
terminated	O
by	O
a	O
second	O
null	O
character	O
.	O
</s>
<s>
The	O
keys	O
at	O
the	O
root	O
level	O
of	O
the	O
hierarchical	B-General_Concept
database	I-General_Concept
are	O
generally	O
named	O
by	O
their	O
Windows	B-Library
API	I-Library
definitions	O
,	O
which	O
all	O
begin	O
"	O
HKEY	B-Protocol
"	O
.	O
</s>
<s>
Technically	O
,	O
they	O
are	O
predefined	O
handles	O
(	O
with	O
known	O
constant	O
values	O
)	O
to	O
specific	O
keys	O
that	O
are	O
either	O
maintained	O
in	O
memory	O
,	O
or	O
stored	O
in	O
hive	O
files	O
stored	O
in	O
the	O
local	O
filesystem	O
and	O
loaded	O
by	O
the	O
system	O
kernel	B-Operating_System
at	O
boot	O
time	O
and	O
then	O
shared	O
(	O
with	O
various	O
access	O
rights	O
)	O
between	O
all	O
processes	O
running	O
on	O
the	O
local	O
system	O
,	O
or	O
loaded	O
and	O
mapped	O
in	O
all	O
processes	O
started	O
in	O
a	O
user	O
session	O
when	O
the	O
user	O
logs	O
on	O
the	O
system	O
.	O
</s>
<s>
The	O
key	O
located	O
by	O
HKLM	O
is	O
actually	O
not	O
stored	O
on	O
disk	O
,	O
but	O
maintained	O
in	O
memory	O
by	O
the	O
system	O
kernel	B-Operating_System
in	O
order	O
to	O
map	O
all	O
the	O
other	O
subkeys	O
.	O
</s>
<s>
On	O
Windows	B-Device
NT	I-Device
,	O
this	O
key	O
contains	O
four	O
subkeys	O
,	O
"	O
SAM	O
"	O
,	O
"	O
SECURITY	O
"	O
,	O
"	O
SYSTEM	O
"	O
,	O
and	O
"	O
SOFTWARE	O
"	O
,	O
that	O
are	O
loaded	O
at	O
boot	O
time	O
within	O
their	O
respective	O
files	O
located	O
in	O
the	O
%SystemRoot%	O
\System32\config	O
folder	O
.	O
</s>
<s>
On	O
Windows	B-Application
Vista	I-Application
and	O
above	O
,	O
a	O
sixth	O
and	O
seventh	O
subkey	O
,	O
"	O
COMPONENTS	O
"	O
and	O
"	O
BCD	O
"	O
,	O
are	O
mapped	O
in	O
memory	O
by	O
the	O
kernel	B-Operating_System
on-demand	O
and	O
loaded	O
from	O
%SystemRoot%	O
\system32\config\COMPONENTS	O
or	O
from	O
boot	O
configuration	O
data	O
,	O
\boot\BCD	O
on	O
the	O
system	O
partition	O
.	O
</s>
<s>
It	O
is	O
used	O
to	O
reference	O
all	O
"	O
Security	O
Accounts	O
Manager	O
"	O
(	O
SAM	O
)	O
databases	O
for	O
all	O
domains	O
into	O
which	O
the	O
local	O
system	O
has	O
been	O
administratively	O
authorized	O
or	O
configured	O
(	O
including	O
the	O
local	O
domain	B-General_Concept
of	O
the	O
running	O
system	O
,	O
whose	O
SAM	O
database	O
is	O
stored	O
in	O
a	O
subkey	O
also	O
named	O
"	O
SAM	O
"	O
:	O
other	O
subkeys	O
will	O
be	O
created	O
as	O
needed	O
,	O
one	O
for	O
each	O
supplementary	O
domain	B-General_Concept
)	O
.	O
</s>
<s>
Each	O
SAM	O
database	O
contains	O
all	O
builtin	O
accounts	O
(	O
mostly	O
group	O
aliases	O
)	O
and	O
configured	O
accounts	O
(	O
users	O
,	O
groups	O
and	O
their	O
aliases	O
,	O
including	O
guest	O
accounts	O
and	O
administrator	O
accounts	O
)	O
created	O
and	O
configured	O
on	O
the	O
respective	O
domain	B-General_Concept
,	O
for	O
each	O
account	O
in	O
that	O
domain	B-General_Concept
,	O
it	O
notably	O
contains	O
the	O
user	O
name	O
which	O
can	O
be	O
used	O
to	O
log	O
on	O
that	O
domain	B-General_Concept
,	O
the	O
internal	O
unique	O
user	O
identifier	O
in	O
the	O
domain	B-General_Concept
,	O
a	O
cryptographic	B-Algorithm
hash	I-Algorithm
of	O
each	O
user	O
's	O
password	O
for	O
each	O
enabled	O
authentication	B-Protocol
protocol	I-Protocol
,	O
the	O
location	O
of	O
storage	O
of	O
their	O
user	O
registry	O
hive	O
,	O
various	O
status	O
flags	O
(	O
for	O
example	O
if	O
the	O
account	O
can	O
be	O
enumerated	O
and	O
be	O
visible	O
in	O
the	O
logon	O
prompt	O
screen	O
)	O
,	O
and	O
the	O
list	O
of	O
domains	O
(	O
including	O
the	O
local	O
domain	B-General_Concept
)	O
into	O
which	O
the	O
account	O
was	O
configured	O
.	O
</s>
<s>
The	O
"	O
HKLM	O
\SECURITY	O
 "	O
key	O
usually	O
appears	O
empty	O
for	O
most	O
users	O
(	O
unless	O
they	O
are	O
granted	O
access	O
by	O
users	O
with	O
administrative	O
privileges	O
)	O
and	O
is	O
linked	O
to	O
the	O
Security	O
database	O
of	O
the	O
domain	B-General_Concept
into	O
which	O
the	O
current	O
user	O
is	O
logged	O
on	O
(	O
if	O
the	O
user	O
is	O
logged	O
on	O
the	O
local	O
system	O
domain	B-General_Concept
,	O
this	O
key	O
will	O
be	O
linked	O
to	O
the	O
registry	O
hive	O
stored	O
by	O
the	O
local	O
machine	O
and	O
managed	O
by	O
local	O
system	O
administrators	O
or	O
by	O
the	O
builtin	O
"	O
System	O
"	O
account	O
and	O
Windows	O
installers	O
)	O
.	O
</s>
<s>
The	O
kernel	B-Operating_System
will	O
access	O
it	O
to	O
read	O
and	O
enforce	O
the	O
security	O
policy	O
applicable	O
to	O
the	O
current	O
user	O
and	O
all	O
applications	O
or	O
operations	O
executed	O
by	O
this	O
user	O
.	O
</s>
<s>
It	O
also	O
contains	O
a	O
"	O
SAM	O
"	O
subkey	O
which	O
is	O
dynamically	O
linked	O
to	O
the	O
SAM	O
database	O
of	O
the	O
domain	B-General_Concept
onto	O
which	O
the	O
current	O
user	O
is	O
logged	O
on	O
.	O
</s>
<s>
It	O
contains	O
information	O
about	O
the	O
Windows	O
system	O
setup	O
,	O
data	O
for	O
the	O
secure	O
random	O
number	O
generator	O
(	O
RNG	O
)	O
,	O
the	O
list	O
of	O
currently	O
mounted	O
devices	O
containing	O
a	O
filesystem	O
,	O
several	O
numbered	O
"	O
HKLM	O
\SYSTEM\Control	O
Sets	O
"	O
containing	O
alternative	O
configurations	O
for	O
system	O
hardware	B-Application
drivers	I-Application
and	O
services	O
running	O
on	O
the	O
local	O
system	O
(	O
including	O
the	O
currently	O
used	O
one	O
and	O
a	O
backup	O
)	O
,	O
a	O
"	O
HKLM	O
\SYSTEM\Select	O
 "	O
subkey	O
containing	O
the	O
status	O
of	O
these	O
Control	O
Sets	O
,	O
and	O
a	O
"	O
HKLM	O
\SYSTEM\CurrentControlSet	O
 "	O
which	O
is	O
dynamically	O
linked	O
at	O
boot	O
time	O
to	O
the	O
Control	O
Set	O
which	O
is	O
currently	O
used	O
on	O
the	O
local	O
system	O
.	O
</s>
<s>
a	O
"	O
Control	O
"	O
subkey	O
organizing	O
the	O
various	O
hardware	B-Application
drivers	I-Application
and	O
programs	O
running	O
as	O
services	O
and	O
all	O
other	O
system-wide	O
configuration	O
,	O
</s>
<s>
It	O
is	O
organized	O
by	O
software	O
vendor	O
(	O
with	O
a	O
subkey	O
for	O
each	O
)	O
,	O
but	O
also	O
contains	O
a	O
"	O
Windows	O
"	O
subkey	O
for	O
some	O
settings	O
of	O
the	O
Windows	O
user	O
interface	O
,	O
a	O
"	O
Classes	O
"	O
subkey	O
containing	O
all	O
registered	O
associations	O
from	O
file	O
extensions	O
,	O
MIME	O
types	O
,	O
Object	O
Classes	O
IDs	O
and	O
interfaces	O
IDs	O
(	O
for	O
OLE	B-Operating_System
,	O
COM/DCOM	O
and	O
ActiveX	O
)	O
,	O
to	O
the	O
installed	O
applications	O
or	O
DLLs	O
that	O
may	O
be	O
handling	O
these	O
types	O
on	O
the	O
local	O
machine	O
(	O
however	O
these	O
associations	O
are	O
configurable	O
for	O
each	O
user	O
,	O
see	O
below	O
)	O
,	O
and	O
a	O
"	O
Policies	O
"	O
subkey	O
(	O
also	O
organized	O
by	O
vendor	O
)	O
for	O
enforcing	O
general	O
usage	O
policies	O
on	O
applications	O
and	O
system	O
services	O
(	O
including	O
the	O
central	O
certificates	O
store	O
used	O
for	O
authenticating	O
,	O
authorizing	O
or	O
disallowing	O
remote	O
systems	O
or	O
services	O
running	O
outside	O
the	O
local	O
network	O
domain	B-General_Concept
)	O
.	O
</s>
<s>
The	O
"	O
HKLM	O
\SOFTWARE\Wow6432Node	O
 "	O
key	O
is	O
used	O
by	O
32-bit	O
applications	O
on	O
a	O
64-bit	O
Windows	B-Application
OS	I-Application
,	O
and	O
is	O
equivalent	O
to	O
but	O
separate	O
from	O
"	O
HKLM	O
\SOFTWARE	O
 "	O
.	O
</s>
<s>
Abbreviated	O
HKCR	O
,	O
HKEY_CLASSES_ROOT	O
contains	O
information	O
about	O
registered	O
applications	O
,	O
such	O
as	O
file	O
associations	O
and	O
OLE	B-Operating_System
Object	I-Operating_System
Class	O
IDs	O
,	O
tying	O
them	O
to	O
the	O
applications	O
used	O
to	O
handle	O
these	O
items	O
.	O
</s>
<s>
On	O
Windows	B-Application
2000	I-Application
and	O
above	O
,	O
HKCR	O
is	O
a	O
compilation	O
of	O
user-based	O
HKCU	O
\Software\Classes	O
and	O
machine-based	O
HKLM	O
\Software\Classes	O
.	O
</s>
<s>
The	O
design	O
allows	O
for	O
either	O
machine	O
-	O
or	O
user-specific	O
registration	O
of	O
COM	B-Application
objects	I-Application
.	O
</s>
<s>
On	O
Windows	B-Device
NT	I-Device
systems	O
,	O
each	O
user	O
's	O
settings	O
are	O
stored	O
in	O
their	O
own	O
files	O
called	O
NTUSER.DAT	O
and	O
USRCLASS.DAT	O
inside	O
their	O
own	O
Documents	B-Application
and	I-Application
Settings	I-Application
subfolder	O
(	O
or	O
their	O
own	O
Users	O
sub	O
folder	O
in	O
Windows	B-Application
Vista	I-Application
and	O
above	O
)	O
.	O
</s>
<s>
Settings	O
in	O
this	O
hive	O
follow	O
users	O
with	O
a	O
roaming	B-General_Concept
profile	I-General_Concept
from	O
machine	O
to	O
machine	O
.	O
</s>
<s>
This	O
key	O
provides	O
runtime	O
information	O
into	O
performance	O
data	O
provided	O
by	O
either	O
the	O
NT	O
kernel	B-Operating_System
itself	O
,	O
or	O
running	O
system	O
drivers	O
,	O
programs	O
and	O
services	O
that	O
provide	O
performance	O
data	O
.	O
</s>
<s>
This	O
key	O
is	O
not	O
stored	O
in	O
any	O
hive	O
and	O
not	O
displayed	O
in	O
the	O
Registry	B-Protocol
Editor	I-Protocol
,	O
but	O
it	O
is	O
visible	O
through	O
the	O
registry	O
functions	O
in	O
the	O
Windows	B-Library
API	I-Library
,	O
or	O
in	O
a	O
simplified	O
view	O
via	O
the	O
Performance	O
tab	O
of	O
the	O
Task	O
Manager	O
(	O
only	O
for	O
a	O
few	O
performance	O
data	O
on	O
the	O
local	O
system	O
)	O
or	O
via	O
more	O
advanced	O
control	O
panels	O
(	O
such	O
as	O
the	O
Performances	O
Monitor	O
or	O
the	O
Performances	O
Analyzer	O
which	O
allows	O
collecting	O
and	O
logging	O
these	O
data	O
,	O
including	O
from	O
remote	O
systems	O
)	O
.	O
</s>
<s>
This	O
key	O
is	O
used	O
only	O
in	O
Windows	B-Application
95	I-Application
,	O
Windows	B-Device
98	I-Device
and	O
Windows	B-Device
ME	I-Device
.	O
</s>
<s>
Even	O
though	O
the	O
registry	O
presents	O
itself	O
as	O
an	O
integrated	O
hierarchical	B-General_Concept
database	I-General_Concept
,	O
branches	O
of	O
the	O
registry	O
are	O
actually	O
stored	O
in	O
a	O
number	O
of	O
disk	O
files	O
called	O
hives	O
.	O
</s>
<s>
The	O
registry	O
is	O
physically	O
stored	O
in	O
several	O
files	O
,	O
which	O
are	O
generally	O
obfuscated	O
from	O
the	O
user-mode	O
APIs	B-Application
used	O
to	O
manipulate	O
the	O
data	O
inside	O
the	O
registry	O
.	O
</s>
<s>
The	O
location	O
for	O
system	B-Protocol
registry	I-Protocol
files	O
in	O
Windows	B-Device
NT	I-Device
is	O
%SystemRoot%	O
\System32\Config	O
;	O
the	O
user-specific	O
HKEY_CURRENT_USER	O
user	O
registry	O
hive	O
is	O
stored	O
in	O
Ntuser.dat	O
inside	O
the	O
user	O
profile	O
.	O
</s>
<s>
There	O
is	O
one	O
of	O
these	O
per	O
user	O
;	O
if	O
a	O
user	O
has	O
a	O
roaming	B-General_Concept
profile	I-General_Concept
,	O
then	O
this	O
file	O
will	O
be	O
copied	O
to	O
and	O
from	O
a	O
server	B-Application
at	O
logout	O
and	O
login	O
respectively	O
.	O
</s>
<s>
A	O
second	O
user-specific	O
registry	O
file	O
named	O
UsrClass.dat	O
contains	O
COM	B-Application
registry	O
entries	O
and	O
does	O
not	O
roam	O
by	O
default	O
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
systems	O
store	O
the	O
registry	O
in	O
a	O
binary	O
file	O
format	O
which	O
can	O
be	O
exported	O
,	O
loaded	O
and	O
unloaded	O
by	O
the	O
Registry	B-Protocol
Editor	I-Protocol
in	O
these	O
operating	O
systems	O
.	O
</s>
<s>
The	O
following	O
system	B-Protocol
registry	I-Protocol
files	O
are	O
stored	O
in	O
%SystemRoot%	O
\System32\Config\	O
:	O
</s>
<s>
For	O
Windows	B-Application
2000	I-Application
,	O
Server	B-Application
2003	O
and	O
Windows	O
XP	O
,	O
the	O
following	O
additional	O
user-specific	O
file	O
is	O
used	O
for	O
file	O
associations	O
and	O
COM	B-Application
information	O
:	O
</s>
<s>
For	O
Windows	B-Application
Vista	I-Application
and	O
later	O
,	O
the	O
path	O
was	O
changed	O
to	O
:	O
</s>
<s>
Windows	B-Application
2000	I-Application
keeps	O
an	O
alternate	O
copy	O
of	O
the	O
registry	O
hives	O
(	O
.ALT	O
)	O
and	O
attempts	O
to	O
switch	O
to	O
it	O
when	O
corruption	O
is	O
detected	O
.	O
</s>
<s>
Windows	O
XP	O
and	O
Windows	O
Server	B-Application
2003	O
do	O
not	O
maintain	O
a	O
System.alt	O
hive	O
because	O
NTLDR	B-Application
on	O
those	O
versions	O
of	O
Windows	O
can	O
process	O
the	O
System.log	O
file	O
to	O
bring	O
up	O
to	O
date	O
a	O
System	O
hive	O
that	O
has	O
become	O
inconsistent	O
during	O
a	O
shutdown	O
or	O
crash	O
.	O
</s>
<s>
Each	O
registry	O
data	O
file	O
has	O
an	O
associated	O
file	O
with	O
a	O
"	O
.log	O
"	O
extension	O
that	O
acts	O
as	O
a	O
transaction	B-General_Concept
log	I-General_Concept
that	O
is	O
used	O
to	O
ensure	O
that	O
any	O
interrupted	O
updates	O
can	O
be	O
completed	O
upon	O
next	O
startup	O
.	O
</s>
<s>
The	O
registry	O
files	O
are	O
stored	O
in	O
the	O
%WINDIR%	O
directory	O
under	O
the	O
names	O
USER.DAT	O
and	O
SYSTEM.DAT	O
with	O
the	O
addition	O
of	O
CLASSES.DAT	O
in	O
Windows	B-Device
ME	I-Device
.	O
</s>
<s>
Note	O
:	O
InterOp	O
Tools	O
also	O
includes	O
a	O
registry	B-Protocol
editor	I-Protocol
.	O
</s>
<s>
This	O
is	O
usually	O
done	O
by	O
using	O
RegEdit.exe	B-Protocol
.	O
</s>
<s>
problems	O
when	O
logging	O
onto	O
a	O
domain	B-General_Concept
can	O
be	O
resolved	O
by	O
editing	O
the	O
registry	O
.	O
</s>
<s>
Windows	B-Protocol
Registry	I-Protocol
can	O
be	O
edited	O
manually	O
using	O
programs	O
such	O
as	O
RegEdit.exe	B-Protocol
,	O
although	O
these	O
tools	O
do	O
not	O
expose	O
some	O
of	O
the	O
registry	O
's	O
metadata	O
such	O
as	O
the	O
last	O
modified	O
date	O
.	O
</s>
<s>
The	O
registry	B-Protocol
editor	I-Protocol
for	O
the	O
3.1/95	O
series	O
of	O
operating	O
systems	O
is	O
RegEdit.exe	B-Protocol
and	O
for	O
Windows	B-Device
NT	I-Device
it	O
is	O
RegEdt32.exe	B-Protocol
;	O
the	O
functionalities	O
are	O
merged	O
in	O
Windows	O
XP	O
.	O
</s>
<s>
Optional	O
and/or	O
third-party	O
tools	O
similar	O
to	O
RegEdit.exe	B-Protocol
are	O
available	O
for	O
many	O
Windows	O
CE	O
versions	O
.	O
</s>
<s>
Registry	B-Protocol
Editor	I-Protocol
allows	O
users	O
to	O
perform	O
the	O
following	O
functions	O
:	O
</s>
<s>
.REG	O
files	O
(	O
also	O
known	O
as	O
Registration	O
entries	O
)	O
are	O
text-based	O
human-readable	O
files	O
for	O
exporting	O
and	O
importing	O
portions	O
of	O
the	O
registry	O
using	O
an	O
INI-based	O
syntax	O
.	O
</s>
<s>
On	O
Windows	B-Application
2000	I-Application
and	O
later	O
,	O
they	O
contain	O
the	O
string	O
Windows	B-Protocol
Registry	I-Protocol
Editor	O
Version	O
5.00	O
at	O
the	O
beginning	O
and	O
are	O
Unicode-based	O
.	O
</s>
<s>
On	O
Windows	O
9x	O
and	O
NT	B-Device
4.0	I-Device
systems	O
,	O
they	O
contain	O
the	O
string	O
REGEDIT4	O
and	O
are	O
ANSI-based	O
.	O
</s>
<s>
Windows	O
9x	O
format	O
.REG	O
files	O
are	O
compatible	O
with	O
Windows	B-Application
2000	I-Application
and	O
later	O
.	O
</s>
<s>
The	O
Registry	B-Protocol
Editor	I-Protocol
on	O
Windows	O
on	O
these	O
systems	O
also	O
supports	O
exporting	O
.REG	O
files	O
in	O
Windows	O
9x/NT	O
format	O
.	O
</s>
<s>
Data	O
from	O
.REG	O
files	O
can	O
be	O
added/merged	O
with	O
the	O
registry	O
by	O
double-clicking	O
these	O
files	O
or	O
using	O
the	O
/s	O
switch	O
in	O
the	O
command	B-Application
line	I-Application
.	O
</s>
<s>
REG	B-Protocol
files	I-Protocol
can	O
also	O
be	O
used	O
to	O
remove	O
registry	O
data	O
.	O
</s>
<s>
Windows	O
group	O
policies	O
can	O
change	O
registry	B-Protocol
keys	I-Protocol
for	O
a	O
number	O
of	O
machines	O
or	O
individual	O
users	O
based	O
on	O
policies	O
.	O
</s>
<s>
More	O
advanced	O
rules	O
can	O
be	O
set	O
up	O
using	O
Windows	B-Library
Management	I-Library
Instrumentation	I-Library
expressions	O
.	O
</s>
<s>
The	O
registry	O
can	O
be	O
manipulated	O
in	O
a	O
number	O
of	O
ways	O
from	O
the	O
command	B-Application
line	I-Application
.	O
</s>
<s>
Also	O
,	O
a	O
.REG	O
file	O
can	O
be	O
imported	O
from	O
the	O
command	B-Application
line	I-Application
with	O
the	O
following	O
command	B-Application
:	O
</s>
<s>
In	O
Windows	B-Device
98	I-Device
,	O
Windows	B-Application
95	I-Application
and	O
at	O
least	O
some	O
configurations	O
of	O
Windows	O
XP	O
the	O
/s	O
switch	O
also	O
causes	O
RegEdit.exe	B-Protocol
to	O
ignore	O
the	O
setting	O
in	O
the	O
registry	O
that	O
allows	O
administrators	O
to	O
disable	O
it	O
.	O
</s>
<s>
When	O
using	O
the	O
/s	O
switch	O
RegEdit.exe	B-Protocol
does	O
not	O
return	O
an	O
appropriate	O
return	O
code	O
if	O
the	O
operation	O
fails	O
,	O
unlike	O
Reg.exe	O
which	O
does	O
.	O
</s>
<s>
Other	O
command	B-Application
line	I-Application
options	I-Application
include	O
a	O
VBScript	B-Application
or	O
JScript	B-Language
together	O
with	O
CScript	O
,	O
WMI	B-Library
or	O
WMIC.exe	O
and	O
Windows	B-Application
PowerShell	I-Application
.	O
</s>
<s>
Registry	O
permissions	O
can	O
be	O
manipulated	O
through	O
the	O
command	B-Application
line	I-Application
using	O
RegIni.exe	O
and	O
the	O
SubInACL.exe	O
tool	O
.	O
</s>
<s>
Windows	B-Application
PowerShell	I-Application
comes	O
with	O
a	O
registry	O
provider	O
which	O
presents	O
the	O
registry	O
as	O
a	O
location	O
type	O
similar	O
to	O
the	O
file	O
system	O
.	O
</s>
<s>
Also	O
like	O
the	O
file	O
system	O
,	O
PowerShell	B-Application
uses	O
the	O
concept	O
of	O
a	O
current	O
location	O
which	O
defines	O
the	O
context	O
on	O
which	O
commands	O
by	O
default	O
operate	O
.	O
</s>
<s>
By	O
using	O
the	O
Set-Location	O
(	O
or	O
the	O
alias	O
cd	O
)	O
command	B-Application
the	O
user	O
can	O
change	O
the	O
current	O
location	O
to	O
another	O
key	O
of	O
the	O
registry	O
.	O
</s>
<s>
Through	O
PowerShell	B-Application
scripts	O
files	O
,	O
an	O
administrator	O
can	O
prepare	O
scripts	O
which	O
,	O
when	O
executed	O
,	O
make	O
changes	O
to	O
the	O
registry	O
.	O
</s>
<s>
The	O
PowerShell	B-Application
Registry	O
provider	O
supports	O
transactions	O
,	O
i.e.	O
</s>
<s>
multiple	O
changes	O
to	O
the	O
registry	O
can	O
be	O
bundled	O
into	O
a	O
single	O
atomic	B-General_Concept
transaction	I-General_Concept
.	O
</s>
<s>
An	O
atomic	B-General_Concept
transaction	I-General_Concept
ensures	O
that	O
either	O
all	O
of	O
the	O
changes	O
are	O
committed	O
to	O
the	O
database	O
,	O
or	O
if	O
the	O
script	O
fails	O
,	O
none	O
of	O
the	O
changes	O
are	O
committed	O
to	O
the	O
database	O
.	O
</s>
<s>
The	O
registry	O
can	O
be	O
edited	O
through	O
the	O
APIs	B-Application
of	O
the	O
Advanced	B-Device
Windows	I-Device
32	O
Base	O
API	B-Application
Library	O
(	O
advapi32.dll	O
)	O
.	O
</s>
<s>
List	O
of	O
registry	O
API	B-Application
functions	I-Application
:	O
</s>
<s>
Many	O
programming	O
languages	O
offer	O
built-in	O
runtime	B-Library
library	I-Library
functions	O
or	O
classes	O
that	O
wrap	O
the	O
underlying	O
Windows	B-Library
APIs	I-Library
and	O
thereby	O
enable	O
programs	O
to	O
store	O
settings	O
in	O
the	O
registry	O
(	O
e.g.	O
</s>
<s>
Microsoft.Win32.Registry	O
in	O
VB.NET	B-Language
and	O
C#	B-Application
,	O
or	O
TRegistry	O
in	O
Delphi	B-Language
and	O
Free	B-Operating_System
Pascal	I-Operating_System
)	O
.	O
</s>
<s>
COM-enabled	O
applications	O
like	O
Visual	B-Language
Basic	I-Language
6	I-Language
can	O
use	O
the	O
WSH	O
WScript.Shell	O
object	O
.	O
</s>
<s>
Similarly	O
,	O
scripting	B-Language
languages	I-Language
such	O
as	O
Perl	B-Language
(	O
with	O
Win32::TieRegistry	O
)	O
,	O
Python	B-Language
(	O
with	O
winreg	O
)	O
,	O
TCL	B-Operating_System
(	O
which	O
comes	O
bundled	O
with	O
the	O
registry	O
package	O
)	O
,	O
Windows	B-Application
Powershell	I-Application
and	O
Windows	O
Scripting	O
Host	O
also	O
enable	O
registry	O
editing	O
from	O
scripts	O
.	O
</s>
<s>
The	O
offreg.dll	O
available	O
from	O
the	O
Windows	B-Application
Driver	I-Application
Kit	I-Application
offers	O
a	O
set	O
of	O
APIs	B-Application
for	O
the	O
creation	O
and	O
manipulation	O
of	O
currently	O
not	O
loaded	O
registry	O
hives	O
similar	O
to	O
those	O
provided	O
by	O
advapi32.dll	O
.	O
</s>
<s>
It	O
is	O
also	O
possible	O
to	O
edit	O
the	O
registry	O
(	O
hives	O
)	O
of	O
an	O
offline	O
system	O
from	O
Windows	O
PE	O
or	O
Linux	B-Application
(	O
in	O
the	O
latter	O
case	O
using	O
open	B-License
source	I-License
tools	O
)	O
.	O
</s>
<s>
Prior	O
to	O
the	O
introduction	O
of	O
registration-free	O
COM	B-Application
,	O
developers	O
were	O
encouraged	O
to	O
add	O
initialization	O
code	O
to	O
in-process	O
and	O
out-of-process	O
binaries	O
to	O
perform	O
the	O
registry	O
configuration	O
required	O
for	O
that	O
object	O
to	O
work	O
.	O
</s>
<s>
For	O
in-process	O
binaries	O
such	O
as	O
.DLL	O
and	O
.OCX	B-Operating_System
files	O
,	O
the	O
modules	O
typically	O
exported	O
a	O
function	O
called	O
DllInstall( )	O
that	O
could	O
be	O
called	O
by	O
installation	O
programs	O
or	O
invoked	O
manually	O
with	O
utilities	O
like	O
Regsvr32.exe	O
;	O
out-of-process	O
binaries	O
typically	O
support	O
the	O
commandline	B-Application
arguments	O
/Regserver	O
and	O
/Unregserver	O
that	O
created	O
or	O
deleted	O
the	O
required	O
registry	O
settings	O
.	O
</s>
<s>
COM	B-Application
applications	O
that	O
break	O
because	O
of	O
DLL	O
Hell	O
issues	O
can	O
commonly	O
be	O
repaired	O
with	O
RegSvr32.exe	O
or	O
the	O
/RegServer	O
switch	O
without	O
having	O
to	O
re-invoke	O
installation	O
programs	O
.	O
</s>
<s>
Windows	O
exposes	O
APIs	B-Application
that	O
allows	O
user-mode	O
applications	O
to	O
register	O
to	O
receive	O
a	O
notification	O
event	O
if	O
a	O
particular	O
registry	B-Protocol
key	I-Protocol
is	O
changed	O
.	O
</s>
<s>
APIs	B-Application
are	O
also	O
available	O
to	O
allow	O
kernel-mode	O
applications	O
to	O
filter	O
and	O
modify	O
registry	O
calls	O
made	O
by	O
other	O
applications	O
.	O
</s>
<s>
Windows	O
also	O
supports	O
remote	O
access	O
to	O
the	O
registry	O
of	O
another	O
computer	O
via	O
the	O
RegConnectRegistry	O
function	O
if	O
the	O
Remote	B-Protocol
Registry	I-Protocol
service	O
is	O
running	O
,	O
correctly	O
configured	O
and	O
its	O
network	O
traffic	O
is	O
not	O
firewalled	O
.	O
</s>
<s>
Each	O
key	O
in	O
the	O
registry	O
of	O
Windows	B-Device
NT	I-Device
versions	O
can	O
have	O
an	O
associated	O
security	O
descriptor	O
.	O
</s>
<s>
+Registry	O
permissionsPermissionDescriptionQuery	O
ValueThe	O
right	O
to	O
read	O
the	O
registry	B-Protocol
key	I-Protocol
value.Set	O
ValueThe	O
right	O
to	O
write	O
a	O
new	O
valueCreate	O
SubkeyThe	O
right	O
to	O
create	O
subkeys.Enumerate	O
SubkeysAllow	O
the	O
enumeration	O
of	O
subkeys.NotifyThe	O
right	O
to	O
request	O
change	O
notifications	O
for	O
registry	B-Protocol
keys	I-Protocol
or	O
subkeys.Create	O
LinkReserved	O
by	O
the	O
operating	O
system.DeleteThe	O
right	O
to	O
delete	O
a	O
key.Write	O
DACLThe	O
right	O
to	O
modify	O
permissions	O
of	O
the	O
container	O
's	O
DACL.Write	O
OwnerThe	O
right	O
to	O
modify	O
the	O
container	O
's	O
owner.Read	O
ControlThe	O
right	O
to	O
read	O
the	O
DACL	O
.	O
</s>
<s>
Windows	O
Resource	O
Protection	O
is	O
a	O
feature	O
of	O
Windows	B-Application
Vista	I-Application
and	O
later	O
versions	O
of	O
Windows	O
that	O
uses	O
security	O
to	O
deny	O
Administrators	O
and	O
the	O
system	O
WRITE	O
access	O
to	O
some	O
sensitive	O
keys	O
to	O
protect	O
the	O
integrity	O
of	O
the	O
system	O
from	O
malware	O
and	O
accidental	O
modification	O
.	O
</s>
<s>
Special	O
ACEs	O
on	O
the	O
security	O
descriptor	O
can	O
also	O
implement	O
mandatory	O
integrity	O
control	O
for	O
the	O
registry	B-Protocol
key	I-Protocol
and	O
subkeys	O
.	O
</s>
<s>
For	O
instance	O
,	O
Internet	B-Application
Explorer	I-Application
running	O
in	O
Protected	O
Mode	O
can	O
read	O
medium	O
and	O
low	O
integrity	O
registry	O
keys/values	O
of	O
the	O
currently	O
logged	O
on	O
user	O
,	O
but	O
it	O
can	O
only	O
modify	O
low	O
integrity	O
keys	O
.	O
</s>
<s>
Outside	O
security	O
,	O
registry	B-Protocol
keys	I-Protocol
cannot	O
be	O
deleted	O
or	O
edited	O
due	O
to	O
other	O
causes	O
.	O
</s>
<s>
Registry	B-Protocol
keys	I-Protocol
containing	O
NUL	O
characters	O
cannot	O
be	O
deleted	O
with	O
standard	O
registry	B-Protocol
editors	I-Protocol
and	O
require	O
a	O
special	O
utility	O
for	O
deletion	O
,	O
such	O
as	O
RegDelNull	O
.	O
</s>
<s>
System	O
Restore	O
can	O
back	O
up	O
the	O
registry	O
and	O
restore	O
it	O
as	O
long	O
as	O
Windows	O
is	O
bootable	O
,	O
or	O
from	O
the	O
Windows	O
Recovery	O
Environment	O
(	O
starting	O
with	O
Windows	B-Application
Vista	I-Application
)	O
.	O
</s>
<s>
Automated	B-General_Concept
System	I-General_Concept
Recovery	I-General_Concept
in	O
Windows	O
XP	O
can	O
also	O
restore	O
the	O
registry	O
.	O
</s>
<s>
On	O
Windows	B-Device
NT	I-Device
,	O
the	O
Last	O
Known	O
Good	O
Configuration	O
option	O
in	O
startup	O
menu	O
relinks	O
the	O
HKLM	O
\SYSTEM\CurrentControlSet	O
key	O
,	O
which	O
stores	O
hardware	O
and	O
device	B-Application
driver	I-Application
information	O
.	O
</s>
<s>
Windows	B-Device
98	I-Device
and	O
Windows	B-Device
ME	I-Device
include	O
command	B-Application
line	I-Application
(	O
Scanreg.exe	O
)	O
and	O
GUI	B-Application
(	O
Scanregw.exe	O
)	O
registry	O
checker	O
tools	O
to	O
check	O
and	O
fix	O
the	O
integrity	O
of	O
the	O
registry	O
,	O
create	O
up	O
to	O
five	O
automatic	O
regular	O
backups	O
by	O
default	O
and	O
restore	O
them	O
manually	O
or	O
whenever	O
corruption	O
is	O
detected	O
.	O
</s>
<s>
The	O
registry	O
checker	O
tool	O
backs	O
up	O
the	O
registry	O
,	O
by	O
default	O
,	O
to	O
%Windir%	O
\Sysbckup	O
Scanreg.exe	O
can	O
also	O
run	O
from	O
MS-DOS	B-Application
.	O
</s>
<s>
The	O
Windows	B-Application
95	I-Application
CD-ROM	O
included	O
an	O
Emergency	O
Recovery	O
Utility	O
(	O
ERU.exe	O
)	O
and	O
a	O
Configuration	O
Backup	O
Tool	O
(	O
Cfgback.exe	O
)	O
to	O
back	O
up	O
and	O
restore	O
the	O
registry	O
.	O
</s>
<s>
Additionally	O
Windows	B-Application
95	I-Application
backs	O
up	O
the	O
registry	O
to	O
the	O
files	O
system.da0	O
and	O
user.da0	O
on	O
every	O
successful	O
boot	O
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
4.0	I-Device
included	O
RDISK.EXE	O
,	O
a	O
utility	O
to	O
back	O
up	O
and	O
restore	O
the	O
entire	O
registry	O
.	O
</s>
<s>
Windows	B-Application
2000	I-Application
Resource	O
Kit	O
contained	O
an	O
unsupported	O
pair	O
of	O
utilities	O
called	O
Regback.exe	O
and	O
RegRest.exe	O
for	O
backup	O
and	O
recovery	O
of	O
the	O
registry	O
.	O
</s>
<s>
Periodic	O
automatic	O
backups	O
of	O
the	O
registry	O
are	O
now	O
disabled	O
by	O
default	O
on	O
Windows	B-Operating_System
10	I-Operating_System
May	O
2019	O
Update	O
(	O
version	O
1903	O
)	O
.	O
</s>
<s>
Windows	B-Application
2000	I-Application
and	O
later	O
versions	O
of	O
Windows	O
use	O
Group	O
Policy	O
to	O
enforce	O
registry	O
settings	O
through	O
a	O
registry-specific	O
client	O
extension	O
in	O
the	O
Group	O
Policy	O
processing	O
engine	O
.	O
</s>
<s>
Policy	O
may	O
be	O
applied	O
locally	O
to	O
a	O
single	O
computer	O
using	O
gpedit.msc	O
,	O
or	O
to	O
multiple	O
users	O
and/or	O
computers	O
in	O
a	O
domain	B-General_Concept
using	O
gpmc.msc	O
.	O
</s>
<s>
With	O
Windows	B-Application
95	I-Application
,	O
Windows	B-Device
98	I-Device
,	O
Windows	B-Device
ME	I-Device
and	O
Windows	B-Device
NT	I-Device
4.0	I-Device
,	O
administrators	O
can	O
use	O
a	O
special	O
file	O
to	O
be	O
merged	O
into	O
the	O
registry	O
,	O
called	O
a	O
policy	O
file	O
(	O
POLICY.POL	O
)	O
.	O
</s>
<s>
The	O
policy	O
file	O
allows	O
administrators	O
to	O
prevent	O
non-administrator	O
users	O
from	O
changing	O
registry	O
settings	O
like	O
,	O
for	O
instance	O
,	O
the	O
security	O
level	O
of	O
Internet	B-Application
Explorer	I-Application
and	O
the	O
desktop	O
background	O
wallpaper	O
.	O
</s>
<s>
The	O
policy	O
file	O
is	O
created	O
by	O
a	O
free	O
tool	O
by	O
Microsoft	O
that	O
goes	O
by	O
the	O
filename	O
poledit.exe	O
for	O
Windows	O
95/Windows	O
98	O
and	O
with	O
a	O
computer	O
management	O
module	O
for	O
Windows	B-Device
NT	I-Device
.	O
</s>
<s>
The	O
editor	O
can	O
also	O
directly	O
change	O
the	O
current	O
registry	O
settings	O
of	O
the	O
local	O
computer	O
and	O
if	O
the	O
remote	B-Protocol
registry	I-Protocol
service	O
is	O
installed	O
and	O
started	O
on	O
another	O
computer	O
it	O
can	O
also	O
change	O
the	O
registry	O
on	O
that	O
computer	O
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
kernels	B-Operating_System
support	O
redirection	O
of	O
INI	O
file-related	O
APIs	B-Application
into	O
a	O
virtual	O
file	O
in	O
a	O
registry	O
location	O
such	O
as	O
HKEY_CURRENT_USER	O
using	O
a	O
feature	O
called	O
"	O
InifileMapping	O
"	O
.	O
</s>
<s>
This	O
functionality	O
was	O
introduced	O
to	O
allow	O
legacy	O
applications	O
written	O
for	O
16-bit	B-Device
versions	O
of	O
Windows	O
to	O
be	O
able	O
to	O
run	O
under	O
Windows	B-Device
NT	I-Device
platforms	O
on	O
which	O
the	O
System	O
folder	O
is	O
no	O
longer	O
considered	O
an	O
appropriate	O
location	O
for	O
user-specific	O
data	O
or	O
configuration	O
.	O
</s>
<s>
Non-compliant	O
32-bit	O
applications	O
can	O
also	O
be	O
redirected	O
in	O
this	O
manner	O
,	O
even	O
though	O
the	O
feature	O
was	O
originally	O
intended	O
for	O
16-bit	B-Device
applications	O
.	O
</s>
<s>
Windows	B-Application
Vista	I-Application
introduced	O
limited	O
registry	O
virtualization	O
,	O
whereby	O
poorly	O
written	O
applications	O
that	O
do	O
not	O
respect	O
the	O
principle	O
of	O
least	O
privilege	O
and	O
instead	O
try	O
to	O
write	O
user	O
data	O
to	O
a	O
read-only	O
system	O
location	O
(	O
such	O
as	O
the	O
HKEY_LOCAL_MACHINE	O
hive	O
)	O
,	O
are	O
silently	O
redirected	O
to	O
a	O
more	O
appropriate	O
location	O
,	O
without	O
changing	O
the	O
application	O
itself	O
.	O
</s>
<s>
Similarly	O
,	O
application	B-Operating_System
virtualization	I-Operating_System
redirects	O
all	O
of	O
an	O
application	O
's	O
invalid	O
registry	O
operations	O
to	O
a	O
location	O
such	O
as	O
a	O
file	O
.	O
</s>
<s>
For	O
example	O
,	O
Internet	B-Application
Explorer	I-Application
7	O
or	O
8	O
running	O
in	O
"	O
Protected	O
Mode	O
"	O
on	O
Windows	B-Application
Vista	I-Application
and	O
above	O
will	O
automatically	O
redirect	O
registry	O
writes	O
by	O
ActiveX	O
controls	O
to	O
a	O
sandboxed	O
location	O
in	O
order	O
to	O
frustrate	O
some	O
classes	O
of	O
security	O
exploits	O
.	O
</s>
<s>
The	O
Application	O
Compatibility	O
Toolkit	O
provides	O
shims	B-General_Concept
that	O
can	O
transparently	O
redirect	O
HKEY_LOCAL_MACHINE	O
or	O
HKEY_CLASSES_ROOT	O
Registry	O
operations	O
to	O
HKEY_CURRENT_USER	O
to	O
address	O
"	O
LUA	O
"	O
bugs	O
that	O
cause	O
applications	O
not	O
to	O
work	O
for	O
users	O
with	O
insufficient	O
rights	O
.	O
</s>
<s>
Critics	O
labeled	O
the	O
registry	O
in	O
Windows	B-Application
95	I-Application
a	O
single	B-Architecture
point	I-Architecture
of	I-Architecture
failure	I-Architecture
,	O
because	O
re-installation	O
of	O
the	O
operating	O
system	O
was	O
required	O
if	O
the	O
registry	O
became	O
corrupt	O
.	O
</s>
<s>
However	O
,	O
Windows	B-Device
NT	I-Device
uses	O
transaction	B-General_Concept
logs	I-General_Concept
to	O
protect	O
against	O
corruption	O
during	O
updates	O
.	O
</s>
<s>
Microsoft	O
provides	O
programming	B-Application
interfaces	I-Application
for	O
storing	O
data	O
in	O
XML	B-Protocol
files	O
(	O
via	O
MSXML	B-Application
)	O
or	O
database	O
files	O
(	O
via	O
SQL	B-Operating_System
Server	I-Operating_System
Compact	I-Operating_System
)	O
which	O
developers	O
can	O
use	O
instead	O
.	O
</s>
<s>
Developers	O
are	O
also	O
free	O
to	O
use	O
non-Microsoft	O
alternatives	O
or	O
develop	O
their	O
own	O
proprietary	B-Application
data	O
stores	O
.	O
</s>
<s>
In	O
contrast	O
to	O
Windows	B-Protocol
Registry	I-Protocol
's	O
binary-based	O
database	O
model	O
,	O
some	O
other	O
operating	O
systems	O
use	O
separate	O
plain-text	O
files	O
for	O
daemon	B-Operating_System
and	O
application	O
configuration	O
,	O
but	O
group	O
these	O
configurations	O
together	O
for	O
ease	O
of	O
management	O
.	O
</s>
<s>
In	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
(	O
including	O
Linux	B-Application
)	O
that	O
follow	O
the	O
Filesystem	B-Application
Hierarchy	I-Application
Standard	I-Application
,	O
system-wide	O
configuration	O
files	O
(	O
information	O
similar	O
to	O
what	O
would	O
appear	O
in	O
HKEY_LOCAL_MACHINE	O
on	O
Windows	O
)	O
are	O
traditionally	O
stored	O
in	O
files	O
in	O
/etc/	O
and	O
its	O
subdirectories	O
,	O
or	O
sometimes	O
in	O
/usr/local/etc	O
.	O
</s>
<s>
Per-user	O
information	O
(	O
information	O
that	O
would	O
be	O
roughly	O
equivalent	O
to	O
that	O
in	O
HKEY_CURRENT_USER	O
)	O
is	O
stored	O
in	O
hidden	B-Application
directories	I-Application
and	I-Application
files	I-Application
(	O
that	O
start	O
with	O
a	O
period/full	O
stop	O
)	O
within	O
the	O
user	O
's	O
home	B-Application
directory	I-Application
.	O
</s>
<s>
However	O
XDG-compliant	O
applications	O
should	O
refer	O
to	O
the	O
environment	O
variables	O
defined	O
in	O
the	O
Base	O
Directory	O
specification	O
.	O
</s>
<s>
In	O
macOS	B-Operating_System
,	O
system-wide	O
configuration	O
files	O
are	O
typically	O
stored	O
in	O
the	O
/Library/	O
folder	O
,	O
whereas	O
per-user	O
configuration	O
files	O
are	O
stored	O
in	O
the	O
corresponding	O
~	O
/Library/	O
folder	O
in	O
the	O
user	O
's	O
home	B-Application
directory	I-Application
,	O
and	O
configuration	O
files	O
set	O
by	O
the	O
system	O
are	O
in	O
/System/Library/	O
.	O
</s>
<s>
Within	O
these	O
respective	O
directories	O
,	O
an	O
application	O
typically	O
stores	O
a	O
property	B-Application
list	I-Application
file	O
in	O
the	O
Preferences/	O
sub-directory	O
.	O
</s>
<s>
RISC	B-Operating_System
OS	I-Operating_System
(	O
not	O
to	O
be	O
confused	O
with	O
MIPS	B-Operating_System
RISC/os	I-Operating_System
)	O
uses	O
directories	O
for	O
configuration	O
data	O
,	O
which	O
allows	O
applications	O
to	O
be	O
copied	O
into	O
application	B-Application
directories	I-Application
,	O
as	O
opposed	O
to	O
the	O
separate	O
installation	O
process	O
that	O
typifies	O
Windows	B-Application
applications	I-Application
;	O
this	O
approach	O
is	O
also	O
used	O
on	O
the	O
ROX	B-Language
Desktop	I-Language
for	O
Linux	B-Application
.	O
</s>
<s>
It	O
is	O
possible	O
to	O
copy	O
installed	O
programs	O
between	O
computers	O
running	O
RISC	B-Operating_System
OS	I-Operating_System
by	O
copying	O
the	O
application	B-Application
directories	I-Application
belonging	O
to	O
the	O
programs	O
,	O
however	O
some	O
programs	O
may	O
require	O
re-installing	O
,	O
e.g.	O
</s>
<s>
when	O
shared	O
files	O
are	O
placed	O
outside	O
an	O
application	B-Application
directory	I-Application
.	O
</s>
<s>
IBM	B-Application
AIX	I-Application
(	O
a	O
Unix	O
variant	O
)	O
uses	O
a	O
registry	O
component	O
called	O
Object	O
Data	O
Manager	O
(	O
ODM	O
)	O
.	O
</s>
<s>
The	O
GNOME	B-Application
desktop	I-Application
environment	I-Application
uses	O
a	O
registry-like	O
interface	O
called	O
dconf	B-Language
for	O
storing	O
configuration	O
settings	O
for	O
the	O
desktop	O
and	O
applications	O
.	O
</s>
<s>
While	O
not	O
an	O
operating	O
system	O
,	O
the	O
Wine	B-Application
compatibility	I-Application
layer	I-Application
,	O
which	O
allows	O
Windows	O
software	O
to	O
run	O
on	O
a	O
Unix-like	B-Operating_System
system	I-Operating_System
,	O
also	O
employs	O
a	O
Windows-like	O
registry	O
as	O
text	B-General_Concept
files	I-General_Concept
in	O
the	O
WINEPREFIX	O
folder	O
:	O
system.reg	O
(	O
HKEY_LOCAL_MACHINE	O
)	O
,	O
user.reg	O
(	O
HKEY_CURRENT_USER	O
)	O
and	O
userdef.reg	O
.	O
</s>
