<s>
In	O
wide	O
area	O
network	O
computing	O
,	O
Link	B-Protocol
Access	I-Protocol
Procedure	I-Protocol
for	I-Protocol
Frame	I-Protocol
Relay	I-Protocol
(	O
or	O
LAPF	B-Protocol
)	O
is	O
part	O
of	O
the	O
network	O
's	O
communications	O
protocol	O
which	O
ensures	O
that	O
frames	O
are	O
error	O
free	O
and	O
executed	O
in	O
the	O
right	O
sequence	O
.	O
</s>
<s>
LAPF	B-Protocol
is	O
formally	O
defined	O
in	O
the	O
International	O
Telecommunication	O
Union	O
standard	O
Q.922	O
.	O
</s>
<s>
It	O
was	O
derived	O
from	O
IBM	O
's	O
Synchronous	B-Protocol
Data	I-Protocol
Link	I-Protocol
Control	I-Protocol
protocol	O
,	O
which	O
is	O
the	O
layer	O
2	O
protocol	O
for	O
IBM	O
's	O
Systems	B-Architecture
Network	I-Architecture
Architecture	I-Architecture
developed	O
around	O
1975	O
.	O
</s>
<s>
ITU	O
used	O
SDLC	O
as	O
a	O
basis	O
to	O
develop	O
LAPF	B-Protocol
for	O
the	O
Frame	B-Protocol
Relay	I-Protocol
environment	O
,	O
along	O
with	O
other	O
equivalents	O
:	O
LAPB	B-Protocol
for	O
the	O
X.25	B-Protocol
protocol	O
stack	O
,	O
LAPM	B-Protocol
for	O
the	O
V.42	O
protocol	O
,	O
and	O
LAPD	O
for	O
the	O
ISDN	B-Protocol
protocol	O
stack	O
.	O
</s>
<s>
In	O
Frame	B-Protocol
Relay	I-Protocol
Local	B-Protocol
Management	I-Protocol
Interface	I-Protocol
(	O
LMI	O
)	O
messages	O
are	O
carried	O
in	O
a	O
variant	O
of	O
LAPF	B-Protocol
frames	O
.	O
</s>
<s>
LAPF	B-Protocol
corresponds	O
to	O
the	O
OSI	O
model	O
Data	O
Link	O
layer	O
.	O
</s>
