<s>
I/O	B-Device
request	I-Device
packets	I-Device
(	O
IRPs	O
)	O
are	O
kernel	O
mode	O
structures	O
that	O
are	O
used	O
by	O
Windows	B-Application
Driver	I-Application
Model	I-Application
(	O
WDM	O
)	O
and	O
Windows	B-Device
NT	I-Device
device	B-Application
drivers	I-Application
to	O
communicate	O
with	O
each	O
other	O
and	O
with	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
The	O
I/O	B-Device
request	I-Device
packet	I-Device
mechanism	O
is	O
also	O
used	O
by	O
Digital	O
Equipment	O
Corporation	O
's	O
VMS	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
,	O
and	O
was	O
used	O
by	O
Digital	O
's	O
RSX-11	B-Application
family	O
of	O
operating	B-General_Concept
systems	I-General_Concept
before	O
that	O
.	O
</s>
<s>
An	O
I/O	B-Device
request	I-Device
packet	I-Device
in	O
RSX-11	B-Application
is	O
called	O
a	O
directive	O
parameter	O
block	O
,	O
as	O
it	O
is	O
also	O
used	O
for	O
system	O
calls	O
other	O
than	O
I/O	O
calls	O
.	O
</s>
