<s>
Portable	B-Application
Batch	I-Application
System	I-Application
(	O
or	O
simply	O
PBS	O
)	O
is	O
the	O
name	O
of	O
computer	O
software	O
that	O
performs	O
job	B-General_Concept
scheduling	I-General_Concept
.	O
</s>
<s>
It	O
is	O
often	O
used	O
in	O
conjunction	O
with	O
UNIX	B-Application
cluster	B-Architecture
environments	O
.	O
</s>
<s>
PBS	O
is	O
supported	O
as	O
a	O
job	B-General_Concept
scheduler	I-General_Concept
mechanism	O
by	O
several	O
meta	O
schedulers	O
including	O
Moab	O
by	O
Adaptive	O
Computing	O
Enterprises	O
and	O
GRAM	O
(	O
Grid	B-Operating_System
Resource	I-Operating_System
Allocation	I-Operating_System
Manager	I-Operating_System
)	O
,	O
a	O
component	O
of	O
the	O
Globus	O
Toolkit	O
.	O
</s>
<s>
OpenPBS	B-Application
—	O
original	O
open	B-Application
source	I-Application
version	O
released	O
by	O
MRJ	O
in	O
1998	O
.	O
</s>
<s>
TORQUE	O
—	O
a	O
fork	O
of	O
OpenPBS	B-Application
that	O
is	O
maintained	O
by	O
Adaptive	O
Computing	O
Enterprises	O
,	O
Inc	O
.	O
(	O
formerly	O
Cluster	B-Architecture
Resources	O
,	O
Inc	O
.	O
)	O
</s>
<s>
PBS	O
Professional	O
(	O
PBS	B-Application
Pro	I-Application
)	O
—	O
the	O
version	O
of	O
PBS	O
offered	O
by	O
Altair	O
Engineering	O
that	O
is	O
dual	O
licensed	O
under	O
an	O
open	B-Application
source	I-Application
and	O
a	O
commercial	O
license	O
.	O
</s>
<s>
Note	O
that	O
the	O
non-commercial	O
offering	O
is	O
called	O
OpenPBS	B-Application
,	O
not	O
to	O
be	O
confused	O
with	O
the	O
outdated	O
software	O
originally	O
released	O
in	O
1998	O
.	O
</s>
<s>
Prior	O
to	O
2002	O
,	O
PBS	O
and	O
derivative	O
programs	O
(	O
OpenPBS	B-Application
)	O
prohibited	O
commercial	O
redistribution	O
of	O
the	O
software	O
,	O
required	O
registration	O
at	O
the	O
OpenPBS	B-Application
website	O
,	O
and	O
required	O
attribution	O
when	O
PBS	O
contributed	O
to	O
a	O
published	O
research	O
project	O
.	O
</s>
<s>
These	O
requirements	O
,	O
which	O
did	O
not	O
meet	O
the	O
Open	B-Application
Source	I-Application
Initiative	O
's	O
definition	O
of	O
open	B-Application
source	I-Application
,	O
were	O
set	O
to	O
expire	O
on	O
December	O
31	O
,	O
2001	O
.	O
</s>
<s>
Today	O
,	O
OpenPBS	B-Application
,	O
the	O
"	O
community	O
edition	O
"	O
of	O
PBS	O
Professional	O
,	O
is	O
distributed	O
under	O
GNU	B-Application
Affero	I-Application
General	I-Application
Public	I-Application
License	I-Application
.	O
</s>
