<s>
X.75	B-Protocol
is	O
an	O
International	O
Telecommunication	O
Union	O
(	O
ITU	O
)	O
(	O
formerly	O
CCITT	O
)	O
standard	O
specifying	O
the	O
interface	O
for	O
interconnecting	O
two	O
X.25	B-Protocol
networks	O
.	O
</s>
<s>
X.75	B-Protocol
is	O
almost	O
identical	O
to	O
X.25	B-Protocol
.	O
</s>
<s>
The	O
significant	O
difference	O
is	O
that	O
while	O
X.25	B-Protocol
specifies	O
the	O
interface	O
between	O
a	O
subscriber	O
(	O
Data	O
Terminal	O
Equipment	O
(	O
DTE	O
)	O
)	O
and	O
the	O
network	O
(	O
Data	O
Circuit-terminating	O
Equipment	O
(	O
DCE	O
)	O
)	O
,	O
X.75	B-Protocol
specifies	O
the	O
interface	O
between	O
two	O
networks	O
(	O
Signalling	O
Terminal	O
Equipment	O
(	O
STE	O
)	O
)	O
,	O
and	O
refers	O
to	O
these	O
two	O
STE	O
as	O
STE-X	O
and	O
STE-Y	O
.	O
</s>
<s>
This	O
gives	O
rise	O
to	O
some	O
subtle	O
differences	O
in	O
the	O
protocol	O
compared	O
with	O
X.25	B-Protocol
.	O
</s>
<s>
For	O
example	O
,	O
X.25	B-Protocol
only	O
allows	O
network-generated	O
reset	O
and	O
clearing	O
causes	O
to	O
be	O
passed	O
from	O
the	O
network	O
(	O
DCE	O
)	O
to	O
the	O
subscriber	O
(	O
DTE	O
)	O
,	O
and	O
not	O
the	O
other	O
way	O
around	O
since	O
the	O
subscriber	O
is	O
not	O
a	O
network	O
.	O
</s>
<s>
However	O
,	O
at	O
the	O
interconnection	O
of	O
two	O
X.25	B-Protocol
networks	O
,	O
either	O
network	O
might	O
reset	O
or	O
clear	O
an	O
X.25	B-Protocol
call	O
,	O
so	O
X.75	B-Protocol
allows	O
network-generated	O
reset	O
and	O
clearing	O
causes	O
to	O
be	O
passed	O
in	O
either	O
direction	O
.	O
</s>
<s>
Although	O
outside	O
the	O
scope	O
of	O
both	O
X.25	B-Protocol
and	O
X.75	B-Protocol
which	O
define	O
external	O
interfaces	O
to	O
an	O
X.25	B-Protocol
network	O
,	O
X.75	B-Protocol
can	O
also	O
be	O
found	O
as	O
the	O
protocol	O
operating	O
between	O
switching	O
nodes	O
inside	O
some	O
X.25	B-Protocol
networks	O
.	O
</s>
