<s>
An	O
NTFS	B-Application
reparse	I-Application
point	I-Application
is	O
a	O
type	O
of	O
NTFS	B-Application
file	I-Application
system	I-Application
object	O
.	O
</s>
<s>
It	O
is	O
available	O
with	O
the	O
NTFS	B-Application
v3.0	O
found	O
in	O
Windows	B-Application
2000	I-Application
or	O
later	O
versions	O
.	O
</s>
<s>
Reparse	B-Application
points	I-Application
provide	O
a	O
way	O
to	O
extend	O
the	O
NTFS	B-Application
filesystem	B-Application
.	O
</s>
<s>
A	O
reparse	B-Application
point	I-Application
contains	O
a	O
reparse	O
tag	O
and	O
data	O
that	O
are	O
interpreted	O
by	O
a	O
filesystem	B-Application
filter	I-Application
driver	O
identified	O
by	O
the	O
tag	O
.	O
</s>
<s>
Microsoft	O
includes	O
several	O
default	O
tags	O
including	O
NTFS	B-Application
symbolic	B-Application
links	I-Application
,	O
directory	O
junction	O
points	O
,	O
volume	O
mount	O
points	O
and	O
Unix	B-Protocol
domain	I-Protocol
sockets	I-Protocol
.	O
</s>
<s>
Also	O
,	O
reparse	B-Application
points	I-Application
are	O
used	O
as	O
placeholders	O
for	O
files	O
moved	O
by	O
Windows	B-Application
2000	I-Application
's	O
Remote	O
Storage	O
Hierarchical	B-Application
Storage	I-Application
System	O
.	O
</s>
<s>
They	O
also	O
can	O
act	O
as	O
hard	B-Application
links	I-Application
,	O
but	O
are	O
not	O
limited	O
to	O
pointing	O
to	O
files	O
on	O
the	O
same	O
volume	O
:	O
they	O
can	O
point	O
to	O
directories	O
on	O
any	O
local	O
volume	O
.	O
</s>
<s>
The	O
feature	O
is	O
inherited	O
to	O
ReFS	B-Application
.	O
</s>
<s>
The	O
open	O
source	O
NTFS-3G	B-Application
driver	O
implements	O
built-in	O
support	O
for	O
the	O
link-type	O
reparse	B-Application
points	I-Application
,	O
namely	O
symbolic	B-Application
links	I-Application
and	O
junction	O
points	O
.	O
</s>
<s>
A	O
plugin	O
filter	O
system	O
is	O
available	O
to	O
handle	O
additional	O
types	O
of	O
reparse	B-Application
points	I-Application
,	O
allowing	O
for	O
chunk-deduplicated	O
files	O
,	O
system-compressed	O
files	O
,	O
and	O
OneDrive	B-Application
files	O
to	O
be	O
read	O
.	O
</s>
<s>
A	O
reparse	B-Application
point	I-Application
has	O
the	O
following	O
general	O
structure	O
,	O
in	O
C	O
struct	O
form	O
:	O
</s>
<s>
The	O
reparse	O
tag	O
is	O
unique	O
to	O
each	O
type	O
of	O
reparse	B-Application
point	I-Application
.	O
</s>
<s>
It	O
defines	O
to	O
which	O
reparse	B-Application
point	I-Application
handler	O
(	O
usually	O
a	O
file	B-Application
system	I-Application
filter	I-Application
driver	O
)	O
the	O
I/O	O
manager	O
delegates	O
the	O
processing	O
.	O
</s>
<s>
Volume	O
mount	O
points	O
are	O
similar	O
to	O
Unix	B-Application
mount	O
points	O
,	O
where	O
the	O
root	O
of	O
another	O
file	B-Application
system	I-Application
is	O
attached	O
to	O
a	O
directory	O
.	O
</s>
<s>
In	O
NTFS	B-Application
,	O
this	O
allows	O
additional	O
file	B-Application
systems	I-Application
to	O
be	O
mounted	O
without	O
requiring	O
a	O
separate	O
drive	O
letter	O
(	O
such	O
as	O
C	O
:	O
or	O
D	O
:	O
)	O
for	O
each	O
.	O
</s>
<s>
The	O
file	B-Application
system	I-Application
does	O
not	O
allow	O
volumes	O
to	O
be	O
mutually	O
mounted	O
on	O
each	O
other	O
.	O
</s>
<s>
Mounted	O
volumes	O
may	O
use	O
other	O
file	B-Application
systems	I-Application
than	O
just	O
NTFS	B-Application
,	O
possibly	O
with	O
their	O
own	O
security	O
settings	O
and	O
remapping	O
of	O
access	O
rights	O
according	O
to	O
the	O
remote	O
file	B-Application
system	I-Application
policy	O
.	O
</s>
<s>
This	O
function	O
is	O
conceptually	O
similar	O
to	O
symbolic	B-Application
links	I-Application
to	O
directories	O
in	O
Unix	B-Application
,	O
except	O
that	O
the	O
target	O
in	O
NTFS	B-Application
must	O
always	O
be	O
another	O
directory	O
(	O
typical	O
Unix	B-Application
file	B-Application
systems	I-Application
allow	O
the	O
target	O
of	O
a	O
symbolic	B-Application
link	I-Application
to	O
be	O
any	O
type	O
of	O
file	O
)	O
.	O
</s>
<s>
This	O
additional	O
security	O
restriction	O
has	O
probably	O
been	O
made	O
to	O
avoid	O
users	O
of	O
finding	O
apparent	O
duplicate	O
files	O
in	O
the	O
joined	O
directories	O
and	O
deleting	O
them	O
by	O
error	O
,	O
because	O
the	O
semantics	O
of	O
directory	O
junctions	O
are	O
not	O
the	O
same	O
as	O
for	O
hard	B-Application
links	I-Application
;	O
the	O
reference	O
counting	O
is	O
not	O
used	O
on	O
the	O
target	O
contents	O
and	O
not	O
even	O
on	O
the	O
referenced	O
container	O
itself	O
.	O
</s>
<s>
Directory	O
junctions	O
are	O
soft	B-Application
links	I-Application
(	O
they	O
will	O
persist	O
even	O
if	O
the	O
target	O
directory	O
is	O
removed	O
)	O
,	O
working	O
as	O
a	O
limited	O
form	O
of	O
symbolic	B-Application
links	I-Application
(	O
with	O
an	O
additional	O
restriction	O
on	O
the	O
location	O
of	O
the	O
target	O
)	O
,	O
but	O
it	O
is	O
an	O
optimized	O
version	O
allowing	O
faster	O
processing	O
of	O
the	O
reparse	B-Application
point	I-Application
with	O
which	O
they	O
are	O
implemented	O
,	O
with	O
less	O
overhead	O
than	O
the	O
newer	O
NTFS	B-Application
symbolic	B-Application
links	I-Application
,	O
and	O
can	O
be	O
resolved	O
on	O
the	O
server	O
side	O
(	O
when	O
they	O
are	O
found	O
in	O
remote	O
shared	O
directories	O
)	O
.	O
</s>
<s>
Symbolic	B-Application
links	I-Application
(	O
or	O
soft	B-Application
links	I-Application
)	O
were	O
introduced	O
in	O
Windows	O
Vista	O
.	O
</s>
<s>
Symbolic	B-Application
links	I-Application
are	O
resolved	O
on	O
the	O
client	O
side	O
.	O
</s>
<s>
So	O
when	O
a	O
symbolic	B-Application
link	I-Application
is	O
shared	O
,	O
the	O
target	O
is	O
subject	O
to	O
the	O
access	O
restrictions	O
on	O
the	O
client	O
,	O
and	O
not	O
the	O
server	O
.	O
</s>
<s>
Symbolic	B-Application
links	I-Application
can	O
be	O
created	O
either	O
to	O
files	O
(	O
created	O
with	O
MKLINK	O
symLink	B-Application
targetFilename	O
)	O
or	O
to	O
directories	O
(	O
created	O
with	O
MKLINK	O
/D	O
symLinkD	O
targetDirectory	O
)	O
,	O
but	O
(	O
unlike	O
Unix	B-Application
symbolic	B-Application
links	I-Application
)	O
the	O
semantic	O
of	O
the	O
link	O
must	O
be	O
provided	O
with	O
the	O
created	O
link	O
.	O
</s>
<s>
The	O
target	O
however	O
need	O
not	O
exist	O
or	O
be	O
available	O
when	O
the	O
symbolic	B-Application
link	I-Application
is	O
created	O
:	O
when	O
the	O
symbolic	B-Application
link	I-Application
will	O
be	O
accessed	O
and	O
the	O
target	O
will	O
be	O
checked	O
for	O
availability	O
,	O
NTFS	B-Application
will	O
also	O
check	O
if	O
it	O
has	O
the	O
correct	O
type	O
(	O
file	O
or	O
directory	O
)	O
;	O
it	O
will	O
return	O
a	O
not-found	O
error	O
if	O
the	O
existing	O
target	O
has	O
the	O
wrong	O
type	O
.	O
</s>
<s>
Their	O
definition	O
is	O
persistent	O
on	O
the	O
NTFS	B-Application
volume	O
where	O
they	O
are	O
created	O
(	O
all	O
types	O
of	O
symbolic	B-Application
links	I-Application
can	O
be	O
removed	O
as	O
if	O
they	O
were	O
files	O
,	O
using	O
DEL	O
symLink	B-Application
from	O
a	O
command	O
line	O
prompt	O
or	O
batch	O
)	O
.	O
</s>
<s>
The	O
symbolic	B-Application
link	I-Application
data	O
is	O
similar	O
to	O
mount	O
point	O
data	O
,	O
in	O
that	O
both	O
use	O
an	O
NT	O
namespace	O
path	O
.	O
</s>
<s>
The	O
difference	O
is	O
that	O
symbolic	B-Application
links	I-Application
accepts	O
UNC	O
paths	O
,	O
but	O
not	O
Volume{guid}	O
mounts	O
.	O
</s>
<s>
When	O
the	O
application	O
requests	O
a	O
track	O
to	O
a	O
file	O
or	O
directory	O
,	O
the	O
tracking	O
service	O
creates	O
the	O
OID	O
entry	O
,	O
which	O
points	O
to	O
the	O
file	O
,	O
and	O
file	O
rename	O
,	O
copy	O
or	O
move	O
operation	O
to	O
a	O
NTFS	B-Application
v3	O
volume	O
also	O
copies	O
the	O
object	O
ID	O
.	O
</s>
<s>
Single	B-Application
instance	I-Application
storage	I-Application
,	O
found	O
in	O
Windows	O
Server	O
2000	O
through	O
Windows	O
Storage	O
Server	O
2008	O
,	O
allows	O
identical	O
files	O
to	O
be	O
merged	O
to	O
one	O
file	O
and	O
create	O
references	O
to	O
that	O
merged	O
file	O
.	O
</s>
<s>
SIS	O
consists	O
of	O
a	O
file	B-Application
system	I-Application
filter	I-Application
that	O
manages	O
copies	O
,	O
modification	O
and	O
merges	O
to	O
files	O
;	O
and	O
a	O
user	O
space	O
service	O
(	O
or	O
groveler	O
)	O
that	O
searches	O
for	O
files	O
that	O
are	O
identical	O
and	O
need	O
merging	O
.	O
</s>
<s>
SIS	O
was	O
mainly	O
designed	O
for	O
remote	O
installation	O
servers	O
as	O
these	O
may	O
have	O
multiple	O
installation	O
images	O
that	O
contain	O
many	O
identical	O
files	O
;	O
SIS	O
allows	O
these	O
to	O
be	O
consolidated	O
but	O
,	O
unlike	O
for	O
example	O
hard	B-Application
links	I-Application
,	O
each	O
file	O
remains	O
distinct	O
;	O
changes	O
to	O
one	O
copy	O
of	O
a	O
file	O
will	O
leave	O
others	O
unaltered	O
.	O
</s>
<s>
This	O
is	O
similar	O
to	O
copy-on-write	B-Language
,	O
which	O
is	O
a	O
technique	O
by	O
which	O
memory	O
copying	O
is	O
not	O
really	O
done	O
until	O
one	O
copy	O
is	O
modified	O
.	O
</s>
<s>
Since	O
Windows	O
Server	O
2019	O
,	O
the	O
feature	O
is	O
fully	O
supported	O
on	O
ReFS	B-Application
.	O
</s>
<s>
Hierarchical	B-Application
Storage	I-Application
Management	I-Application
is	O
a	O
means	O
of	O
transferring	O
files	O
that	O
are	O
not	O
used	O
for	O
some	O
period	O
of	O
time	O
to	O
less	O
expensive	O
storage	O
media	O
.	O
</s>
<s>
When	O
the	O
file	O
is	O
next	O
accessed	O
,	O
the	O
reparse	B-Application
point	I-Application
on	O
that	O
file	O
determines	O
that	O
it	O
is	O
needed	O
and	O
retrieves	O
it	O
from	O
storage	O
.	O
</s>
<s>
NSS	O
was	O
an	O
ActiveX	B-Application
document	I-Application
storage	O
technology	O
that	O
has	O
since	O
been	O
discontinued	O
by	O
Microsoft	O
.	O
</s>
<s>
It	O
allowed	O
ActiveX	B-Application
Documents	I-Application
to	O
be	O
stored	O
in	O
the	O
same	O
multi-stream	O
format	O
that	O
ActiveX	B-Application
uses	O
internally	O
.	O
</s>
<s>
An	O
NSS	O
file	B-Application
system	I-Application
filter	I-Application
was	O
loaded	O
and	O
used	O
to	O
process	O
the	O
multiple	O
streams	O
transparently	O
to	O
the	O
application	O
,	O
and	O
when	O
the	O
file	O
was	O
transferred	O
to	O
a	O
non-NTFS	O
formatted	O
disk	O
volume	O
it	O
would	O
also	O
transfer	O
the	O
multiple	O
streams	O
into	O
a	O
single	O
stream	O
.	O
</s>
<s>
With	O
Windows	B-Operating_System
10	I-Operating_System
build	O
17063	O
(	O
for	O
stable	O
release	O
version	O
1803	O
)	O
,	O
Microsoft	O
introduced	O
Unix	B-Protocol
domain	I-Protocol
sockets	I-Protocol
to	O
Windows	O
.	O
</s>
<s>
These	O
are	O
realized	O
by	O
using	O
the	O
afunix.sys	O
kernel	O
driver	O
and	O
a	O
new	O
reparse	B-Application
point	I-Application
in	O
the	O
file	B-Application
system	I-Application
.	O
</s>
<s>
Unix	B-Protocol
domain	I-Protocol
sockets	I-Protocol
are	O
common	O
on	O
BSD	O
and	O
Linux	O
systems	O
and	O
can	O
be	O
seen	O
as	O
the	O
standard	O
for	O
inter	O
process	O
communication	O
on	O
these	O
systems	O
;	O
therefore	O
their	O
introduction	O
to	O
Windows	O
will	O
allow	O
simplified	O
adoption	O
of	O
code	O
and	O
cross-platform	O
portability	O
.	O
</s>
<s>
Windows	B-Operating_System
10	I-Operating_System
introduces	O
read-only	O
CompactOS	O
compression	O
algorithms	O
for	O
NTFS	B-Application
file	I-Application
system	I-Application
,	O
taken	O
from	O
Windows	O
Imaging	O
Format	O
(	O
WIM	O
)	O
;	O
they	O
are	O
designed	O
to	O
compress	O
Windows	O
system	O
files	O
and	O
reduce	O
disk	O
space	O
usage	O
.	O
</s>
<s>
Internally	O
,	O
the	O
compressed	O
file	O
is	O
recorded	O
as	O
a	O
reparse	B-Application
point	I-Application
with	O
tag	O
IO_REPARSE_TAG_WOF	O
(	O
0x80000017	O
)	O
,	O
where	O
WoF	O
stands	O
for	O
Windows	O
Overlay	O
Filter	O
,	O
and	O
the	O
actual	O
data	O
is	O
stored	O
in	O
an	O
alternate	O
data	O
stream	O
named	O
"	O
WofCompressedData	O
"	O
,	O
which	O
is	O
processed	O
by	O
WOF	O
file	B-Application
system	I-Application
filter	I-Application
.	O
</s>
<s>
CompactOS	O
is	O
an	O
improved	O
variant	O
of	O
WIMBoot	O
from	O
Windows	B-Device
8.1	I-Device
,	O
where	O
system	O
files	O
could	O
be	O
stored	O
in	O
a	O
compressed	O
WIM	O
image	O
on	O
a	O
hidden	O
disk	B-Application
partition	I-Application
,	O
and	O
the	O
WOF	O
filter	O
driver	O
would	O
decompress	O
file	O
contents	O
from	O
that	O
WIM	O
file	O
;	O
using	O
alternate	O
data	O
streams	O
instead	O
of	O
read-only	O
WIM	O
images	O
allows	O
CompactOS	O
to	O
recompress	O
system	O
files	O
when	O
they	O
need	O
to	O
be	O
rewritten	O
with	O
an	O
updated	O
version	O
.	O
</s>
<s>
OneDrive	B-Application
tags	O
the	O
files	O
and	O
directories	O
it	O
has	O
downloaded	O
to	O
the	O
local	O
storage	O
as	O
a	O
reparse	B-Application
point	I-Application
with	O
tag	O
0x9000001a	O
.	O
</s>
<s>
The	O
Stuxnet	O
as	O
part	O
of	O
its	O
series	O
of	O
Win32	O
exploits	O
uses	O
NTFS	B-Application
junction	O
points	O
as	O
part	O
of	O
its	O
overall	O
mode	O
of	O
operation	O
.	O
</s>
