<s>
A	O
Warnier/Orr	B-Application
diagram	I-Application
(	O
also	O
known	O
as	O
a	O
logical	O
construction	O
of	O
a	O
program/system	O
)	O
is	O
a	O
kind	O
of	O
hierarchical	O
flowchart	B-Language
that	O
allows	O
the	O
description	O
of	O
the	O
organization	O
of	O
data	O
and	O
procedures	O
.	O
</s>
<s>
This	O
method	O
aids	O
the	O
design	O
of	O
program	B-Language
structures	I-Language
by	O
identifying	O
the	O
output	O
and	O
processing	O
results	O
and	O
then	O
working	O
backwards	O
to	O
determine	O
the	O
steps	O
and	O
combinations	O
of	O
input	O
needed	O
to	O
produce	O
them	O
.	O
</s>
<s>
The	O
simple	O
graphic	O
method	O
used	O
in	O
Warnier/Orr	B-Application
diagrams	I-Application
makes	O
the	O
levels	O
in	O
the	O
system	O
evident	O
and	O
the	O
movement	O
of	O
the	O
data	O
between	O
them	O
vivid	O
.	O
</s>
<s>
Warnier/Orr	B-Application
diagrams	I-Application
show	O
the	O
processes	O
and	O
sequences	O
in	O
which	O
they	O
are	O
performed	O
.	O
</s>
<s>
Since	O
a	O
process	O
can	O
have	O
many	O
different	O
subprocesses	O
,	O
Warnier/Orr	B-Application
diagram	I-Application
uses	O
a	O
set	O
of	O
brackets	O
to	O
show	O
each	O
level	O
of	O
the	O
system	O
.	O
</s>
<s>
Warnier/Orr	B-Application
diagrams	I-Application
show	O
this	O
very	O
well	O
.	O
</s>
<s>
To	O
develop	O
a	O
Warnier/Orr	B-Application
diagram	I-Application
,	O
the	O
analyst	O
works	O
backwards	O
,	O
starting	O
with	O
systems	O
output	O
and	O
using	O
output	O
oriented	O
analysis	O
.	O
</s>
<s>
Warnier/Orr	B-Application
diagrams	I-Application
offer	O
some	O
distinct	O
advantages	O
to	O
systems	O
experts	O
.	O
</s>
<s>
There	O
are	O
four	O
basic	O
constructs	O
used	O
on	O
Warnier/Orr	B-Application
diagrams	I-Application
:	O
hierarchy	O
,	O
sequence	O
,	O
repetition	O
,	O
and	O
alternation	O
.	O
</s>
<s>
Hierarchy	O
is	O
the	O
most	O
fundamental	O
of	O
all	O
of	O
the	O
Warnier/Orr	B-Application
constructs	O
.	O
</s>
<s>
Sequence	O
is	O
the	O
simplest	O
structure	O
to	O
show	O
on	O
a	O
Warnier/Orr	B-Application
diagram	I-Application
.	O
</s>
<s>
On	O
the	O
Warnier/Orr	B-Application
diagram	I-Application
,	O
however	O
,	O
there	O
is	O
no	O
distinction	O
between	O
the	O
two	O
different	O
types	O
of	O
repetition	O
,	O
other	O
than	O
the	O
minimum	O
bound	O
value	O
.	O
</s>
