<s>
The	O
System	B-Operating_System
V	I-Operating_System
Interface	I-Operating_System
Definition	I-Operating_System
(	O
SVID	B-Operating_System
)	O
is	O
a	O
standard	O
that	O
describes	O
the	O
AT&T	B-Operating_System
UNIX	I-Operating_System
System	B-Operating_System
V	I-Operating_System
behavior	O
,	O
including	O
that	O
of	O
system	B-Operating_System
calls	I-Operating_System
,	O
C	B-Language
libraries	I-Language
,	O
available	O
programs	O
and	O
devices	O
.	O
</s>
<s>
While	O
it	O
was	O
not	O
the	O
first	O
attempt	O
at	O
a	O
standardizations	O
document	O
(	O
the	O
industry	O
trade	O
association	O
/usr/group	O
published	O
a	O
standard	O
in	O
1984	O
based	O
on	O
System	B-Operating_System
III	I-Operating_System
with	O
a	O
few	O
system	B-Operating_System
call	I-Operating_System
additions	O
from	O
BSD	B-Operating_System
)	O
,	O
it	O
was	O
an	O
important	O
effort	O
in	O
early	O
standardization	O
of	O
UNIX	O
in	O
a	O
period	O
when	O
UNIX	O
variants	O
were	O
multiplying	O
rapidly	O
and	O
portability	O
was	O
problematic	O
at	O
best	O
.	O
</s>
<s>
By	O
1986	O
,	O
AT&T	O
required	O
conformance	O
with	O
SVID	B-Operating_System
issue	O
2	O
if	O
vendors	O
were	O
to	O
actually	O
brand	O
their	O
products	O
"	O
System	B-Operating_System
V	I-Operating_System
R3	O
"	O
.	O
</s>
<s>
By	O
the	O
1990s	O
,	O
however	O
,	O
its	O
importance	O
was	O
largely	O
eclipsed	O
by	O
POSIX	O
and	O
the	O
Single	O
UNIX	O
Specification	O
,	O
which	O
were	O
based	O
in	O
part	O
upon	O
the	O
SVID	B-Operating_System
.	O
</s>
