<s>
A	O
message	B-Application
sequence	I-Application
chart	I-Application
(	O
or	O
MSC	O
)	O
is	O
an	O
interaction	O
diagram	O
from	O
the	O
SDL	B-Application
family	O
standardized	O
by	O
the	O
International	O
Telecommunication	O
Union	O
.	O
</s>
<s>
The	O
purpose	O
of	O
recommending	O
MSC	O
(	O
Message	B-Application
Sequence	I-Application
Chart	I-Application
)	O
is	O
to	O
provide	O
a	O
trace	O
language	O
for	O
the	O
specification	O
and	O
description	O
of	O
the	O
communication	O
behaviour	O
of	O
system	O
components	O
and	O
their	O
environment	O
by	O
means	O
of	O
message	O
interchange	O
.	O
</s>
<s>
The	O
1996	O
version	O
added	O
references	O
,	O
ordering	O
and	O
inlining	O
expressions	O
concepts	O
,	O
and	O
introduced	O
HMSC	O
(	O
High-level	O
Message	B-Application
Sequence	I-Application
Charts	I-Application
)	O
,	O
which	O
are	O
the	O
way	O
of	O
expressing	O
a	O
sequence	O
of	O
MSCs	O
.	O
</s>
<s>
Data	O
concept	O
:	O
The	O
user	O
can	O
use	O
any	O
data	O
concept	O
,	O
if	O
binding	O
is	O
undefined	O
the	O
default	O
data	O
concept	O
is	O
the	O
one	O
from	O
SDL	B-Application
as	O
defined	O
in	O
Z.121	O
recommendation	O
.	O
</s>
<s>
SDL-RT	B-Application
has	O
introduced	O
:	O
</s>
<s>
UML	B-Language
2.0	I-Language
Sequence	O
Diagram	O
is	O
strongly	O
inspired	O
by	O
the	O
ITU-T	O
MSC	O
.	O
</s>
<s>
It	O
has	O
been	O
said	O
that	O
MSC	O
has	O
been	O
considered	O
as	O
a	O
candidate	O
for	O
the	O
interaction	O
diagrams	O
in	O
UML	B-Language
.	O
</s>
<s>
However	O
,	O
proponents	O
of	O
MSC	O
such	O
as	O
Ericsson	O
think	O
that	O
MSC	O
is	O
better	O
than	O
UML	B-Language
2.0	I-Language
for	O
modelling	O
large	O
or	O
complex	O
systems	O
.	O
</s>
