<s>
The	O
N	O
2	O
chart	O
,	O
also	O
referred	O
to	O
as	O
N	O
2	O
diagram	O
,	O
N-squared	B-Application
diagram	I-Application
or	O
N-squared	O
chart	O
,	O
is	O
a	O
diagram	O
in	O
the	O
shape	O
of	O
a	O
matrix	B-Architecture
,	O
representing	O
functional	O
or	O
physical	O
interfaces	B-Application
between	O
system	O
elements	O
.	O
</s>
<s>
It	O
is	O
used	O
to	O
systematically	O
identify	O
,	O
define	O
,	O
tabulate	O
,	O
design	O
,	O
and	O
analyze	O
functional	O
and	O
physical	O
interfaces	B-Application
.	O
</s>
<s>
It	O
applies	O
to	O
system	O
interfaces	B-Application
and	O
hardware	B-Architecture
and/or	O
software	O
interfaces	B-Application
.	O
</s>
<s>
The	O
N2	B-Application
diagram	I-Application
has	O
been	O
used	O
extensively	O
to	O
develop	O
data	O
interfaces	B-Application
,	O
primarily	O
in	O
the	O
software	O
areas	O
.	O
</s>
<s>
However	O
,	O
it	O
can	O
also	O
be	O
used	O
to	O
develop	O
hardware	B-Architecture
interfaces	B-Application
.	O
</s>
<s>
The	O
basic	O
N2	B-Application
chart	I-Application
is	O
shown	O
in	O
Figure	O
2	O
.	O
</s>
<s>
The	O
system	O
functions	O
are	O
placed	O
on	O
the	O
diagonal	O
;	O
the	O
remainder	O
of	O
the	O
squares	O
in	O
the	O
N×N	O
matrix	B-Architecture
represent	O
the	O
interface	B-Application
inputs	O
and	O
outputs	O
.	O
</s>
<s>
N2	B-Application
chart	I-Application
definition	O
.	O
</s>
<s>
N2	B-Application
Chart	I-Application
Key	O
Features	O
.	O
</s>
<s>
Where	O
a	O
blank	O
appears	O
,	O
there	O
is	O
no	O
interface	B-Application
between	O
the	O
respective	O
functions	O
.	O
</s>
<s>
Alternatively	O
,	O
the	O
use	O
of	O
circles	O
and	O
numbers	O
permits	O
a	O
separate	O
listing	O
of	O
the	O
data	O
interfaces	B-Application
.	O
</s>
<s>
A	O
simple	O
flow	O
of	O
interface	B-Application
data	O
exists	O
between	O
the	O
upper	O
and	O
lower	O
modules	O
at	O
functions	O
F7	O
and	O
F8	O
.	O
</s>
<s>
The	O
N2	B-Application
chart	I-Application
can	O
be	O
taken	O
down	O
into	O
successively	O
lower	O
levels	O
to	O
the	O
hardware	B-Architecture
and	O
software	O
component	O
functional	O
levels	O
.	O
</s>
<s>
In	O
addition	O
to	O
defining	O
the	O
data	O
that	O
must	O
be	O
supplied	O
across	O
the	O
interface	B-Application
,	O
the	O
N2	B-Application
chart	I-Application
can	O
pinpoint	O
areas	O
where	O
conflicts	O
could	O
arise	O
.	O
</s>
<s>
The	O
"	O
N	O
"	O
in	O
an	O
N2	B-Application
diagram	I-Application
is	O
the	O
number	O
of	O
entities	O
for	O
which	O
relationships	O
are	O
shown	O
.	O
</s>
<s>
This	O
N×N	O
matrix	B-Architecture
requires	O
the	O
user	O
to	O
generate	O
complete	O
definitions	O
of	O
all	O
interfaces	B-Application
in	O
a	O
rigid	O
bidirectional	O
,	O
fixed	O
framework	O
.	O
</s>
<s>
The	O
user	O
places	O
the	O
functional	O
or	O
physical	O
entities	O
on	O
the	O
diagonal	O
axis	O
and	O
the	O
interface	B-Application
inputs	O
and	O
outputs	O
in	O
the	O
remainder	O
of	O
the	O
diagram	O
squares	O
.	O
</s>
<s>
A	O
blank	O
square	O
indicates	O
that	O
there	O
is	O
no	O
interface	B-Application
between	O
the	O
respective	O
entities	O
.	O
</s>
<s>
That	O
which	O
passes	O
across	O
the	O
interface	B-Application
is	O
defined	O
in	O
the	O
appropriate	O
squares	O
.	O
</s>
<s>
The	O
N2	B-Application
diagram	I-Application
should	O
be	O
used	O
in	O
each	O
successively	O
lower	O
level	O
of	O
entity	O
decomposition	O
.	O
</s>
<s>
of	O
interfaces	B-Application
between	O
entities	O
within	O
an	O
N2	B-Application
diagram	I-Application
.	O
</s>
<s>
If	O
there	O
is	O
no	O
interface	B-Application
between	O
two	O
functions	O
,	O
the	O
square	O
that	O
represents	O
the	O
interface	B-Application
between	O
the	O
two	O
functions	O
is	O
left	O
blank	O
.	O
</s>
<s>
Physical	O
interfaces	B-Application
would	O
be	O
handled	O
in	O
the	O
same	O
manner	O
,	O
with	O
the	O
physical	O
entities	O
on	O
the	O
diagonal	O
rather	O
than	O
the	O
functional	O
entities	O
.	O
</s>
<s>
Each	O
N2	B-Application
diagram	I-Application
shall	O
contain	O
at	O
a	O
minimum	O
the	O
following	O
contextual	O
and	O
administrative	O
data	O
:	O
</s>
<s>
N2	B-Application
diagrams	I-Application
are	O
a	O
valuable	O
tool	O
for	O
not	O
only	O
identifying	O
functional	O
or	O
physical	O
interfaces	B-Application
,	O
but	O
also	O
for	O
pinpointing	O
areas	O
in	O
which	O
conflicts	O
may	O
arise	O
with	O
interfaces	B-Application
so	O
that	O
system	O
integration	O
proceeds	O
smoothly	O
and	O
efficiently	O
.	O
</s>
<s>
Figure	O
5	O
presents	O
information	O
in	O
an	O
N2	B-Application
diagram	I-Application
,	O
which	O
complements	O
the	O
Functional	O
flow	O
block	O
diagram	O
.	O
</s>
