<s>
Various	O
software	B-Application
package	I-Application
metrics	I-Application
are	O
used	O
in	O
modular	B-Architecture
programming	I-Architecture
.	O
</s>
<s>
The	O
term	O
software	B-Application
package	I-Application
here	O
refers	O
to	O
a	O
group	O
of	O
related	O
classes	O
in	O
object-oriented	B-Language
programming	I-Language
.	O
</s>
<s>
Afferent	B-Application
couplings	I-Application
(	O
Ca	O
)	O
:	O
The	O
number	O
of	O
classes	O
in	O
other	O
packages	O
that	O
depend	O
upon	O
classes	O
within	O
the	O
package	O
is	O
an	O
indicator	O
of	O
the	O
package	O
's	O
responsibility	O
.	O
</s>
<s>
Afferent	B-Application
couplings	I-Application
signal	O
inward	O
.	O
</s>
<s>
Efferent	O
couplings	B-Application
(	O
Ce	O
)	O
:	O
The	O
number	O
of	O
classes	O
in	O
other	O
packages	O
that	O
the	O
classes	O
in	O
a	O
package	O
depend	O
upon	O
is	O
an	O
indicator	O
of	O
the	O
package	O
's	O
dependence	O
on	O
externalities	O
.	O
</s>
<s>
Efferent	O
couplings	B-Application
signal	O
outward	O
.	O
</s>
<s>
Instability	O
(	O
I	O
)	O
:	O
The	O
ratio	O
of	O
efferent	O
coupling	B-Application
(	O
Ce	O
)	O
to	O
total	O
coupling	B-Application
(	O
Ce	O
+	O
Ca	O
)	O
such	O
that	O
I	O
=	O
Ce	O
/	O
(	O
Ce	O
+	O
Ca	O
)	O
.	O
</s>
<s>
Package	O
dependency	B-Application
cycles	O
:	O
Package	O
dependency	B-Application
cycles	O
are	O
reported	O
along	O
with	O
the	O
hierarchical	O
paths	O
of	O
packages	O
participating	O
in	O
package	O
dependency	B-Application
cycles	O
.	O
</s>
