<s>
Control	B-General_Concept
logic	I-General_Concept
is	O
a	O
key	O
part	O
of	O
a	O
software	B-Application
program	I-Application
that	O
controls	O
the	O
operations	O
of	O
the	O
program	B-Application
.	O
</s>
<s>
The	O
control	B-General_Concept
logic	I-General_Concept
responds	O
to	O
commands	O
from	O
the	O
user	O
,	O
and	O
it	O
also	O
acts	O
on	O
its	O
own	O
to	O
perform	O
automated	O
tasks	O
that	O
have	O
been	O
structured	O
into	O
the	O
program	B-Application
.	O
</s>
<s>
Control	B-General_Concept
logic	I-General_Concept
can	O
be	O
modeled	O
using	O
a	O
state	B-Application
diagram	I-Application
,	O
which	O
is	O
a	O
form	O
of	O
hierarchical	O
state	B-Architecture
machine	I-Architecture
.	O
</s>
<s>
These	O
state	B-Application
diagrams	I-Application
can	O
also	O
be	O
combined	O
with	O
flow	B-Language
charts	I-Language
to	O
provide	O
a	O
set	O
of	O
computational	B-General_Concept
semantics	I-General_Concept
for	O
describing	O
complex	O
control	B-General_Concept
logic	I-General_Concept
.	O
</s>
<s>
This	O
mix	O
of	O
state	B-Application
diagrams	I-Application
and	O
flow	B-Language
charts	I-Language
is	O
illustrated	O
in	O
the	O
figure	O
on	O
the	O
right	O
,	O
which	O
shows	O
the	O
control	B-General_Concept
logic	I-General_Concept
for	O
a	O
simple	O
stopwatch	O
.	O
</s>
<s>
The	O
control	B-General_Concept
logic	I-General_Concept
takes	O
in	O
commands	O
from	O
the	O
user	O
,	O
as	O
represented	O
by	O
the	O
event	O
named	O
“	O
START	O
”	O
,	O
but	O
also	O
has	O
automatic	O
recurring	O
sample	O
time	O
events	O
,	O
as	O
represented	O
by	O
the	O
event	O
named	O
“	O
TIC	O
”	O
.	O
</s>
