<s>
Kernel	B-Operating_System
normal	I-Operating_System
form	I-Operating_System
,	O
or	O
KNF	O
,	O
is	O
the	O
coding	B-Language
style	I-Language
used	O
in	O
the	O
development	O
of	O
code	O
for	O
the	O
BSD	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
.	O
</s>
<s>
Based	O
on	O
the	O
original	O
KNF	O
concept	O
from	O
the	O
Computer	B-Operating_System
Systems	I-Operating_System
Research	I-Operating_System
Group	I-Operating_System
,	O
it	O
dictates	O
a	O
programming	B-Language
style	I-Language
to	O
which	O
contributed	O
code	O
should	O
adhere	O
prior	O
to	O
its	O
inclusion	O
into	O
the	O
codebase	B-General_Concept
.	O
</s>
<s>
KNF	O
started	O
out	O
as	O
a	O
codification	O
of	O
how	O
Ken	O
Thompson	O
and	O
Dennis	O
Ritchie	O
formatted	O
the	O
original	O
UNIX	B-Application
C	B-Language
source	O
code	O
.	O
</s>
<s>
It	O
describes	O
such	O
things	O
as	O
how	O
to	O
name	O
variables	O
,	O
use	O
indents	O
and	O
the	O
use	O
of	O
ANSI	O
C	B-Language
or	O
K&R	O
C	B-Language
code	B-Language
styles	I-Language
.	O
</s>
<s>
Each	O
BSD	B-Operating_System
variant	O
has	O
its	O
own	O
KNF	O
rules	O
,	O
which	O
have	O
evolved	O
over	O
time	O
to	O
differ	O
from	O
each	O
other	O
in	O
small	O
ways	O
.	O
</s>
