<s>
Source	B-Device
Code	I-Device
Control	I-Device
System	I-Device
(	O
SCCS	O
)	O
is	O
a	O
version	B-Architecture
control	I-Architecture
system	I-Architecture
designed	O
to	O
track	O
changes	O
in	O
source	O
code	O
and	O
other	O
text	O
files	O
during	O
the	O
development	O
of	O
a	O
piece	O
of	O
software	O
.	O
</s>
<s>
It	O
was	O
originally	O
developed	O
at	O
Bell	O
Labs	O
beginning	O
in	O
late	O
1972	O
by	O
Marc	O
Rochkind	O
for	O
an	O
IBM	B-Device
System/370	I-Device
computer	O
running	O
OS/360	B-Application
.	O
</s>
<s>
This	O
example	O
illustrates	O
its	O
use	O
in	O
the	O
C	B-Language
programming	I-Language
language	I-Language
:	O
</s>
<s>
In	O
1972	O
,	O
Marc	O
Rochkind	O
developed	O
SCCS	O
in	O
SNOBOL4	B-Application
at	O
Bell	O
Labs	O
for	O
an	O
IBM	B-Device
System/370	I-Device
computer	O
running	O
OS/360	B-Application
MVT	O
.	O
</s>
<s>
He	O
rewrote	O
SCCS	O
in	O
the	O
C	B-Language
programming	I-Language
language	I-Language
for	O
use	O
under	O
UNIX	B-Application
,	O
then	O
running	O
on	O
a	O
PDP-11	B-Device
,	O
in	O
1973	O
.	O
</s>
<s>
It	O
was	O
available	O
with	O
the	O
Programmer	B-Operating_System
's	I-Operating_System
Workbench	I-Operating_System
(	O
PWB	O
)	O
edition	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Subsequently	O
,	O
SCCS	O
was	O
included	O
in	O
T	O
's	O
commercial	O
System	B-Operating_System
III	I-Operating_System
and	O
System	B-Operating_System
V	I-Operating_System
distributions	O
.	O
</s>
<s>
It	O
was	O
not	O
licensed	O
with	O
32V	B-Operating_System
,	O
the	O
ancestor	O
to	O
BSD	B-Operating_System
.	O
</s>
<s>
The	O
SCCS	O
command	O
set	O
is	O
now	O
part	O
of	O
the	O
Single	O
UNIX	B-Application
Specification	O
.	O
</s>
<s>
SCCS	O
was	O
the	O
dominant	O
version	B-Architecture
control	I-Architecture
system	I-Architecture
for	O
Unix	B-Application
until	O
later	O
version	B-Architecture
control	I-Architecture
systems	I-Architecture
,	O
notably	O
the	O
RCS	B-Architecture
and	O
later	O
CVS	B-Application
,	O
gained	O
more	O
widespread	O
adoption	O
.	O
</s>
<s>
Today	O
,	O
these	O
early	O
version	B-Architecture
control	I-Architecture
systems	I-Architecture
are	O
generally	O
considered	O
obsolete	O
,	O
particularly	O
in	O
the	O
open-source	B-Application
community	O
,	O
which	O
has	O
largely	O
embraced	O
distributed	B-Protocol
version	I-Protocol
control	I-Protocol
systems	I-Protocol
.	O
</s>
<s>
However	O
,	O
the	O
SCCS	O
file	O
format	O
is	O
still	O
used	O
internally	O
by	O
a	O
few	O
newer	O
version	B-Architecture
control	I-Architecture
programs	O
,	O
including	O
BitKeeper	B-Protocol
and	O
TeamWare	B-Protocol
.	O
</s>
<s>
The	O
SCCS	O
file	O
format	O
uses	O
a	O
storage	O
technique	O
called	O
interleaved	B-Protocol
deltas	I-Protocol
(	O
or	O
the	O
weave	O
)	O
.	O
</s>
<s>
This	O
storage	O
technique	O
is	O
now	O
considered	O
by	O
many	O
version	B-Architecture
control	I-Architecture
system	I-Architecture
developers	O
as	O
foundational	O
to	O
advanced	O
merging	B-General_Concept
and	O
versioning	O
techniques	O
,	O
such	O
as	O
the	O
"	O
Precise	O
Codeville	O
"	O
(	O
"	O
pcdv	O
"	O
)	O
merge	B-General_Concept
.	O
</s>
<s>
Apart	O
from	O
correcting	O
Year	B-Error_Name
2000	I-Error_Name
problems	I-Error_Name
in	O
1999	O
,	O
no	O
active	O
development	O
has	O
taken	O
place	O
on	O
the	O
various	O
UNIX	B-Application
vendor-specific	O
SCCS	O
versions	O
.	O
</s>
<s>
In	O
2006	O
,	O
Sun	O
Microsystems	O
(	O
today	O
part	O
of	O
Oracle	B-Application
)	O
released	O
their	O
Solaris	B-Application
version	O
of	O
SCCS	O
as	O
open-source	B-Application
under	O
the	O
CDDL	B-Application
license	I-Application
as	O
part	O
of	O
their	O
efforts	O
to	O
open-source	B-Application
Solaris	B-Application
.	O
</s>
<s>
The	O
Source	B-Device
Code	I-Device
Control	I-Device
System	I-Device
(	O
SCCS	O
)	O
is	O
a	O
system	O
for	O
controlling	O
file	O
and	O
history	O
changes	O
.	O
</s>
<s>
Software	O
is	O
typically	O
upgraded	B-General_Concept
to	O
a	O
new	O
version	O
by	O
fixing	O
bugs	O
,	O
optimizing	O
algorithms	O
and	O
adding	O
extra	O
functions	O
.	O
</s>
<s>
Changing	O
software	O
causes	O
problems	O
that	O
require	O
version	B-Architecture
control	I-Architecture
to	O
solve	O
.	O
</s>
<s>
Finding	O
the	O
exact	O
version	O
which	O
the	O
client	B-Operating_System
has	O
problems	O
with	O
is	O
difficult	O
.	O
</s>
<s>
Two	O
specific	O
implementations	O
using	O
SCCS	O
are	O
:	O
PDP	B-Device
11	I-Device
under	O
Unix	B-Application
and	O
IBM	B-Device
370	I-Device
under	O
the	O
OS	O
.	O
</s>
<s>
SCCS	O
provides	O
a	O
set	O
of	O
commands	O
in	O
the	O
form	O
of	O
macro	O
invocations	O
that	O
perform	O
or	O
initiate	O
source	B-Architecture
code	I-Architecture
management	I-Architecture
functions	O
with	O
a	O
simple	O
syntax	O
,	O
such	O
as	O
create	O
,	O
get	O
,	O
edit	O
,	O
prt	O
.	O
</s>
<s>
Most	O
UNIX	B-Application
versions	O
include	O
a	O
version	O
of	O
SCCS	O
,	O
which	O
,	O
however	O
,	O
is	O
often	O
no	O
longer	O
actively	O
developed	O
.	O
</s>
<s>
The	O
late	O
(	O
who	O
requested	O
the	O
release	O
of	O
SCCS	O
in	O
the	O
early	O
days	O
of	O
the	O
OpenSolaris	B-Operating_System
project	O
)	O
maintained	O
a	O
fork	B-Application
of	O
SCCS	O
that	O
is	O
based	O
on	O
the	O
OpenSolaris	B-Operating_System
source	O
code	O
.	O
</s>
<s>
The	O
Heirloom	B-Device
Project	I-Device
includes	O
a	O
version	O
of	O
SCCS	O
derived	O
from	O
the	O
OpenSolaris	B-Operating_System
source	O
code	O
and	O
maintained	O
between	O
December	O
2006	O
and	O
April	O
2007	O
.	O
</s>
<s>
GNU	B-Operating_System
offers	O
the	O
SCCS	O
compatible	O
program	O
(	O
"	O
Compatibly	O
Stupid	O
Source	B-Architecture
Control	I-Architecture
"	O
)	O
,	O
which	O
is	O
occasionally	O
used	O
to	O
convert	O
SCCS	O
archives	O
to	O
newer	O
systems	O
like	O
CVS	B-Application
or	O
Subversion	B-Application
;	O
it	O
is	O
not	O
a	O
complete	O
SCCS	O
implementation	O
and	O
not	O
recommended	O
for	O
use	O
in	O
new	O
projects	O
,	O
but	O
mostly	O
meant	O
for	O
converting	O
to	O
a	O
modern	O
version	B-Architecture
control	I-Architecture
system	I-Architecture
.	O
</s>
<s>
Since	O
the	O
1990s	O
,	O
many	B-Protocol
new	I-Protocol
version	I-Protocol
control	I-Protocol
systems	I-Protocol
have	O
been	O
developed	O
and	O
become	O
popular	O
that	O
are	O
designed	O
for	O
managing	O
projects	O
with	O
a	O
large	O
number	O
of	O
files	O
and	O
that	O
offer	O
advanced	O
functionality	O
such	O
as	O
multi-user	O
operation	O
,	O
access	O
control	O
,	O
automatic	O
building	O
,	O
network	O
support	O
,	O
release	O
management	O
and	O
distributed	B-Protocol
version	I-Protocol
control	I-Protocol
.	O
</s>
<s>
Bitkeeper	B-Protocol
and	O
TeamWare	B-Protocol
use	O
the	O
SCCS	O
file	O
format	O
internally	O
and	O
can	O
be	O
considered	O
successors	O
to	O
SCCS	O
.	O
</s>
<s>
On	O
BSD	B-Operating_System
systems	O
,	O
the	O
SCCSID	O
is	O
replaced	O
by	O
a	O
RCSID	O
starting	O
and	O
ending	O
with	O
;	O
the	O
corresponding	O
tool	O
is	O
.	O
</s>
<s>
This	O
system	O
is	O
originally	O
used	O
by	O
RCS	B-Architecture
and	O
added	O
automatically	O
on	O
checkout	O
.	O
</s>
<s>
The	O
resulting	O
source	O
code	O
revision	B-Architecture
control	I-Architecture
identifiers	O
are	O
documented	O
in	O
the	O
NetBSD	B-Device
and	O
FreeBSD	B-Operating_System
style	O
guides	O
for	O
their	O
own	O
code	O
bases	O
.	O
</s>
<s>
NetBSD	B-Device
defines	O
the	O
custom	O
keyword	O
while	O
FreeBSD	B-Operating_System
defines	O
and	O
a	O
macro	O
renamed	O
.	O
</s>
<s>
The	O
SRC	O
version	B-Architecture
control	I-Architecture
system	I-Architecture
can	O
also	O
use	O
the	O
SCCS	O
file	O
format	O
internally	O
(	O
or	O
RCS	B-Architecture
's	O
)	O
and	O
aims	O
to	O
provide	O
a	O
better	O
user	O
interface	O
for	O
SCCS	O
while	O
still	O
managing	O
only	O
single-file	O
projects	O
.	O
</s>
