<s>
The	O
Workplace	B-Device
Shell	I-Device
(	O
WPS	O
)	O
is	O
an	O
object-oriented	B-Language
desktop	O
shell	O
(	O
also	O
called	O
desktop	O
environment	O
)	O
produced	O
by	O
IBM	O
's	O
Boca	O
Raton	O
development	O
lab	O
for	O
OS/2	B-Application
2.0	O
.	O
</s>
<s>
It	O
is	O
based	O
on	O
Common	B-General_Concept
User	I-General_Concept
Access	I-General_Concept
and	O
made	O
a	O
radical	O
shift	O
away	O
from	O
the	O
Program	O
Manager	O
type	O
interface	O
that	O
earlier	O
versions	O
of	O
OS/2	B-Application
shared	O
with	O
Windows	B-Application
3.x	I-Application
or	O
the	O
application-oriented	O
WIMP	B-Application
interface	I-Application
of	O
the	O
Apple	B-Device
Macintosh	I-Device
.	O
</s>
<s>
The	O
Workplace	B-Device
Shell	I-Device
was	O
also	O
used	O
in	O
OS/2	B-Application
Warp	B-Application
3	I-Application
and	O
Warp	O
4	O
,	O
and	O
the	O
OS/2	B-Application
-based	O
operating	O
systems	O
eComStation	B-Device
and	O
ArcaOS	B-Device
.	O
</s>
<s>
IBM	O
originally	O
intended	O
to	O
deliver	O
the	O
Workplace	B-Device
Shell	I-Device
as	O
part	O
of	O
the	O
OfficeVision/2	B-Application
LAN	I-Application
product	O
,	O
but	O
in	O
1991	O
announced	O
plans	O
to	O
release	O
it	O
as	O
part	O
of	O
OS/2	B-Application
2.0	O
instead	O
.	O
</s>
<s>
Although	O
mostly	O
written	O
in	O
C	B-Language
,	O
under	O
the	O
covers	O
the	O
Workplace	B-Device
Shell	I-Device
is	O
implemented	O
as	O
an	O
object-oriented	B-Language
class	O
library	O
,	O
basing	O
on	O
the	O
System	B-Device
Object	I-Device
Model	I-Device
(	O
SOM	O
)	O
.	O
</s>
<s>
The	O
WPS	O
classes	O
are	O
glued	O
together	O
with	O
an	O
interface	B-General_Concept
definition	I-General_Concept
language	I-General_Concept
(	O
IDL	O
)	O
.	O
</s>
<s>
The	O
classes	O
can	O
easily	O
be	O
manipulated	O
by	O
sending	O
simple	O
settings	O
strings	O
(	O
like	O
"	O
KEYWORD	O
=	O
VALUE	O
;	O
"	O
)	O
to	O
them	O
both	O
via	O
a	O
C	B-Language
and	O
a	O
Rexx	B-Language
API	B-General_Concept
.	O
</s>
<s>
Once	O
the	O
new	O
object	O
class	O
implemented	O
by	O
it	O
is	O
registered	O
with	O
the	O
Workplace	B-Device
Shell	I-Device
and	O
an	O
instance	O
of	O
this	O
class	O
is	O
created	O
,	O
it	O
can	O
be	O
acted	O
on	O
by	O
the	O
user	O
or	O
other	O
programs	O
as	O
every	O
other	O
Workplace	B-Device
Shell	I-Device
object	O
.	O
</s>
<s>
A	O
part	O
of	O
the	O
WPS	O
design	O
allows	O
for	O
the	O
developer	O
of	O
a	O
class	O
Y	O
which	O
extends	O
or	O
modifies	O
a	O
class	O
X	B-Operating_System
to	O
execute	O
an	O
additional	O
API	B-General_Concept
on	O
installation	O
which	O
will	O
let	O
the	O
WPS	O
'	O
replace	O
 '	O
class	O
X	B-Operating_System
by	O
class	O
Y	O
.	O
</s>
<s>
This	O
will	O
make	O
even	O
all	O
existing	O
instances	O
of	O
class	O
X	B-Operating_System
behave	O
as	O
instances	O
of	O
the	O
modified	O
class	O
Y	O
;	O
i.e.	O
,	O
almost	O
a	O
retroactive	O
inheritance	B-Language
.	O
</s>
