<s>
A	O
function	B-Application
key	I-Application
is	O
a	O
key	O
on	O
a	O
computer	O
or	O
terminal	B-General_Concept
keyboard	B-Device
that	O
can	O
be	O
programmed	O
so	O
as	O
to	O
cause	O
an	O
operating	O
system	O
command	B-Device
interpreter	O
or	O
application	O
program	O
to	O
perform	O
certain	O
actions	O
,	O
a	O
form	O
of	O
soft	B-General_Concept
key	I-General_Concept
.	O
</s>
<s>
On	O
some	O
keyboards/computers	O
,	O
function	B-Application
keys	I-Application
may	O
have	O
default	O
actions	O
,	O
accessible	O
on	O
power-on	O
.	O
</s>
<s>
Function	B-Application
keys	I-Application
on	O
a	O
terminal	B-General_Concept
may	O
either	O
generate	O
short	O
fixed	O
sequences	O
of	O
characters	O
,	O
often	O
beginning	O
with	O
the	O
escape	O
character	O
(	O
ASCII	B-Protocol
27	O
)	O
,	O
or	O
the	O
characters	O
they	O
generate	O
may	O
be	O
configured	O
by	O
sending	O
special	O
character	O
sequences	O
to	O
the	O
terminal	B-General_Concept
.	O
</s>
<s>
On	O
a	O
standard	O
computer	B-Device
keyboard	I-Device
,	O
the	O
function	B-Application
keys	I-Application
may	O
generate	O
a	O
fixed	O
,	O
single	O
byte	O
code	O
,	O
outside	O
the	O
normal	O
ASCII	B-Protocol
range	O
,	O
which	O
is	O
translated	O
into	O
some	O
other	O
configurable	O
sequence	O
by	O
the	O
keyboard	B-Device
device	O
driver	O
or	O
interpreted	O
directly	O
by	O
the	O
application	O
program	O
.	O
</s>
<s>
Function	B-Application
keys	I-Application
may	O
have	O
abbreviations	O
or	O
pictographic	O
representations	O
of	O
default	O
actions	O
printed	O
on/besides	O
them	O
,	O
or	O
they	O
may	O
have	O
the	O
more	O
common	O
"	O
F-number	O
"	O
designations	O
.	O
</s>
<s>
The	O
Singer/Friden	O
2201	O
Flexowriter	B-Application
Programatic	O
,	O
introduced	O
in	O
1965	O
,	O
had	O
a	O
cluster	O
of	O
13	O
function	B-Application
keys	I-Application
,	O
labeled	O
F1	O
to	O
F13	O
to	O
the	O
right	O
of	O
the	O
main	O
keyboard	B-Device
.	O
</s>
<s>
Although	O
the	O
Flexowriter	B-Application
could	O
be	O
used	O
as	O
a	O
computer	B-General_Concept
terminal	I-General_Concept
,	O
this	O
electromechanical	O
typewriter	O
was	O
primarily	O
intended	O
as	O
a	O
stand-alone	O
word	B-General_Concept
processing	I-General_Concept
system	O
.	O
</s>
<s>
The	O
interpretation	O
of	O
the	O
function	B-Application
keys	I-Application
was	O
determined	O
by	O
the	O
programming	O
of	O
a	O
plugboard	O
inside	O
the	O
back	O
of	O
the	O
machine	O
.	O
</s>
<s>
Soft	B-General_Concept
keys	I-General_Concept
date	O
to	O
avionics	O
multi-function	B-Device
displays	I-Device
of	O
military	O
planes	O
of	O
the	O
late	O
1960s/early	O
1970s	O
,	O
such	O
as	O
the	O
Mark	O
II	O
avionics	O
of	O
the	O
F-111D	O
(	O
first	O
ordered	O
1967	O
,	O
delivered	O
1970	O
–	O
73	O
)	O
.	O
</s>
<s>
In	O
computing	O
use	O
,	O
they	O
were	O
found	O
on	O
the	O
HP	B-Device
9810A	I-Device
calculator	O
(	O
1971	O
)	O
and	O
later	O
models	O
of	O
the	O
HP	B-Device
9800	I-Device
series	I-Device
,	O
which	O
featured	O
10	O
programmable	O
keys	O
in	O
5×2	O
block	O
(	O
2	O
rows	O
of	O
5	O
keys	O
)	O
at	O
the	O
top	O
left	O
of	O
the	O
keyboard	B-Device
,	O
with	O
paper	O
labels	O
.	O
</s>
<s>
The	O
HP	B-Device
9830A	I-Device
(	O
1972	O
)	O
was	O
an	O
early	O
desktop	O
computer	O
,	O
and	O
one	O
of	O
the	O
earliest	O
specifically	O
computing	O
uses	O
.	O
</s>
<s>
HP	O
continued	O
its	O
use	O
of	O
function	B-Application
keys	I-Application
in	O
the	O
HP	B-General_Concept
2640	I-General_Concept
(	O
1975	O
)	O
,	O
which	O
used	O
screen-labeled	B-General_Concept
function	I-General_Concept
keys	I-General_Concept
,	O
placing	O
the	O
keys	O
close	O
to	O
the	O
screen	O
,	O
where	O
labels	O
could	O
be	O
displayed	O
for	O
their	O
function	O
.	O
</s>
<s>
NEC	O
's	O
PC-8001	B-Device
,	O
introduced	O
in	O
1979	O
,	O
featured	O
five	O
function	B-Application
keys	I-Application
at	O
the	O
top	O
of	O
the	O
keyboard	B-Device
,	O
along	O
with	O
a	O
numeric	B-Device
keypad	I-Device
on	O
the	O
right-hand	O
side	O
of	O
the	O
keyboard	B-Device
.	O
</s>
<s>
Their	O
modern	O
use	O
may	O
have	O
been	O
popularized	O
by	O
IBM	O
keyboards	B-Device
:	O
first	O
the	O
IBM	B-Operating_System
3270	I-Operating_System
terminals	O
,	O
then	O
the	O
IBM	B-Device
PC	I-Device
.	O
</s>
<s>
IBM	O
use	O
of	O
function	B-Application
keys	I-Application
dates	O
to	O
the	O
IBM	B-Operating_System
3270	I-Operating_System
line	O
of	O
terminals	O
,	O
specifically	O
the	O
IBM	B-Operating_System
3277	I-Operating_System
(	O
1972	O
)	O
with	O
78-key	O
typewriter	O
keyboard	B-Device
or	O
operator	O
console	O
keyboard	B-Device
version	O
,	O
which	O
both	O
featured	O
12	O
programmed	O
function	O
(	O
PF	O
)	O
keys	O
in	O
a	O
3×4	O
matrix	O
at	O
the	O
right	O
of	O
the	O
keyboard	B-Device
.	O
</s>
<s>
Later	O
models	O
replaced	O
this	O
with	O
a	O
numeric	B-Device
keypad	I-Device
,	O
and	O
moved	O
the	O
function	B-Application
keys	I-Application
to	O
24	O
keys	O
at	O
the	O
top	O
of	O
the	O
keyboard	B-Device
.	O
</s>
<s>
The	O
original	O
IBM	B-Device
PC	I-Device
keyboard	I-Device
(	O
PC/XT	B-Device
,	O
1981	O
)	O
had	O
10	O
function	B-Application
keys	I-Application
(	O
F1	O
–	O
F10	O
)	O
in	O
a	O
2×5	O
matrix	O
at	O
the	O
left	O
of	O
the	O
keyboard	B-Device
;	O
this	O
was	O
replaced	O
by	O
12	O
keys	O
in	O
3	O
blocks	O
of	O
4	O
at	O
the	O
top	O
of	O
the	O
keyboard	B-Device
in	O
the	O
Model	B-Device
M	I-Device
(	O
"	O
Enhanced	O
"	O
,	O
1984	O
)	O
.	O
</s>
<s>
Mac	B-Device
:	O
The	O
classic	B-Application
Mac	I-Application
OS	I-Application
supported	O
system	O
extensions	O
known	O
generally	O
as	O
FKEYS	B-Application
which	O
could	O
be	O
installed	O
in	O
the	O
System	O
file	O
and	O
could	O
be	O
accessed	O
with	O
a	O
Command-Shift-(number )	O
keystroke	O
combination	O
(	O
Command-Shift-3	O
was	O
the	O
screen	B-Application
capture	I-Application
function	O
included	O
with	O
the	O
system	O
,	O
and	O
was	O
installed	O
as	O
an	O
FKEY	B-Application
)	O
;	O
however	O
,	O
early	O
Macintosh	B-Device
keyboards	B-Device
did	O
not	O
support	O
numbered	O
function	B-Application
keys	I-Application
in	O
the	O
normal	O
sense	O
.	O
</s>
<s>
Since	O
the	O
introduction	O
of	O
the	O
Apple	B-Device
Extended	I-Device
Keyboard	I-Device
with	O
the	O
Macintosh	B-Device
II	O
,	O
however	O
,	O
keyboards	B-Device
with	O
function	B-Application
keys	I-Application
have	O
been	O
available	O
,	O
though	O
they	O
did	O
not	O
become	O
standard	O
until	O
the	O
mid-1990s	O
.	O
</s>
<s>
They	O
have	O
not	O
traditionally	O
been	O
a	O
major	O
part	O
of	O
the	O
Mac	B-Device
user	O
interface	O
,	O
however	O
,	O
and	O
are	O
generally	O
only	O
used	O
on	O
cross-platform	O
programs	O
.	O
</s>
<s>
According	O
to	O
the	O
Macintosh	B-Application
Human	I-Application
Interface	I-Application
Guidelines	I-Application
,	O
they	O
are	O
reserved	O
for	O
customization	O
by	O
the	O
user	O
.	O
</s>
<s>
Current	O
Mac	B-Device
keyboards	B-Device
include	O
specialized	O
function	B-Application
keys	I-Application
for	O
controlling	O
sound	O
volume	O
.	O
</s>
<s>
The	O
most	O
recent	O
Mac	B-Device
keyboards	B-Device
include	O
19	O
function	B-Application
keys	I-Application
,	O
but	O
keys	O
F1	O
–	O
F4	O
and	O
F7	O
–	O
F12	O
by	O
default	O
control	O
features	O
such	O
as	O
volume	O
,	O
media	O
control	O
,	O
and	O
Exposé	O
.	O
</s>
<s>
Former	O
keyboards	B-Device
and	O
Apple	B-Device
Keyboard	I-Device
with	O
numeric	B-Device
keypad	I-Device
has	O
the	O
F1	O
–	O
F19	O
keys	O
.	O
</s>
<s>
Mac	B-Device
laptops	O
:	O
Function	B-Application
keys	I-Application
were	O
not	O
standard	O
on	O
Apple	O
notebook	O
hardware	O
until	O
the	O
introduction	O
of	O
the	O
PowerBook	O
5300	O
and	O
the	O
PowerBook	O
190	O
.	O
</s>
<s>
For	O
the	O
most	O
part	O
,	O
Mac	B-Device
laptops	O
have	O
keys	O
F1	O
through	O
F12	O
,	O
with	O
pre-defined	O
actions	O
for	O
some	O
,	O
including	O
controlling	O
sound	O
volume	O
and	O
screen	O
brightness	O
.	O
</s>
<s>
Apricot	O
PC/Xi	O
:	O
six	O
unlabelled	O
keys	O
,	O
each	O
with	O
an	O
LED	O
beside	O
it	O
which	O
illuminates	O
when	O
the	O
key	O
can	O
be	O
used	O
;	O
above	O
the	O
keys	O
is	O
a	O
liquid	B-Device
crystal	I-Device
displaythe	O
'	O
microscreen'that	O
is	O
used	O
by	O
programs	O
to	O
display	O
the	O
action	O
performed	O
by	O
the	O
key	O
.	O
</s>
<s>
Atari	B-Device
8-bit	I-Device
family	I-Device
:	O
four	O
dedicated	O
keys	O
(	O
Reset	O
,	O
Option	O
,	O
Select	O
,	O
Start	O
)	O
at	O
the	O
right	O
hand	O
side	O
or	O
on	O
the	O
top	O
of	O
the	O
keyboard	B-Device
;	O
the	O
XL	O
models	O
also	O
had	O
a	O
Help	B-Protocol
key	I-Protocol
.	O
</s>
<s>
Atari	O
1200XL	B-Device
has	O
four	O
additional	O
keys	O
labeled	O
F1	O
through	O
F4	O
with	O
pre-defined	O
actions	O
,	O
mainly	O
related	O
to	O
cursor	O
movement	O
.	O
</s>
<s>
Atari	B-Device
ST	I-Device
:	O
ten	O
parallelogram-shaped	O
keys	O
in	O
a	O
horizontal	O
row	O
across	O
the	O
top	O
of	O
the	O
keyboard	B-Device
,	O
inset	O
into	O
the	O
keyboard	B-Device
frame	O
instead	O
of	O
popping	O
up	O
like	O
normal	O
keys	O
.	O
</s>
<s>
BBC	B-Device
Micro	I-Device
:	O
red/orange	O
keys	O
F0	O
to	O
F9	O
in	O
a	O
horizontal	O
row	O
above	O
the	O
number	O
keys	O
on	O
top	O
of	O
the	O
computer/keyboard	O
.	O
</s>
<s>
The	O
case	O
included	O
a	O
transparent	O
plastic	O
strip	O
above	O
them	O
to	O
hold	O
a	O
function	B-Application
key	I-Application
reference	O
card	O
.	O
</s>
<s>
Coleco	B-Device
Adam	I-Device
:	O
six	O
dark	O
brown	O
keys	O
in	O
a	O
horizontal	O
row	O
above	O
the	O
number	O
keys	O
,	O
labeled	O
with	O
Roman	O
numerals	O
I	O
–	O
VI	O
.	O
</s>
<s>
VIC-20	B-Device
and	O
Commodore	O
64	O
:	O
F1/F2	O
to	O
F7/F8	O
in	O
a	O
vertical	O
row	O
of	O
four	O
keys	O
descending	O
on	O
the	O
computer/keyboard	O
'	O
s	O
right	O
hand	O
side	O
,	O
odd-numbered	O
functions	O
accessed	O
unshifted	O
,	O
even-numbered	O
shifted	O
;	O
orange	O
,	O
beige/brown	O
,	O
or	O
grey	O
key	O
color	O
,	O
depending	O
on	O
VIC/64	O
model/revision	O
.	O
</s>
<s>
Commodore	B-Device
128	I-Device
:	O
essentially	O
same	O
as	O
VIC-20/C64	O
,	O
but	O
with	O
(	O
grey	O
)	O
function	B-Application
keys	I-Application
placed	O
in	O
a	O
horizontal	O
row	O
above	O
the	O
numeric	B-Device
keypad	I-Device
right	O
of	O
the	O
main	O
QWERTY-keyboard	O
;	O
also	O
had	O
Help	B-Protocol
key	I-Protocol
.	O
</s>
<s>
Commodore	B-Device
Amiga	I-Device
:	O
ten	B-Device
keys	I-Device
arranged	O
in	O
a	O
row	O
of	O
two	O
five-key	O
groups	O
across	O
the	O
top	O
of	O
the	O
keyboard	B-Device
(	O
flush	O
with	O
the	O
ordinary	O
keyboard	B-Device
top	O
row	O
)	O
;	O
function	B-Application
keys	I-Application
are	O
1½	O
times	O
the	O
width	O
of	O
ordinary	O
keys	O
.	O
</s>
<s>
Like	O
the	O
Commodore	B-Device
128	I-Device
,	O
this	O
also	O
had	O
a	O
Help	B-Protocol
key	I-Protocol
.	O
</s>
<s>
Graphing	B-Application
calculators	I-Application
,	O
particularly	O
those	O
from	O
Texas	O
Instruments	O
,	O
Hewlett-Packard	O
and	O
Casio	O
,	O
usually	O
include	O
a	O
row	O
of	O
function	B-Application
keys	I-Application
with	O
various	O
preassigned	O
functions	O
(	O
on	O
a	O
standard	O
hand-held	O
calculator	O
,	O
these	O
would	O
be	O
the	O
top	O
row	O
of	O
buttons	O
under	O
the	O
screen	O
)	O
.	O
</s>
<s>
On	O
low-end	O
models	O
such	O
as	O
the	O
TI-83-series	O
,	O
these	O
function	O
mainly	O
as	O
an	O
extension	O
of	O
the	O
main	O
keyboard	B-Device
,	O
but	O
on	O
high-end	O
calculators	O
the	O
functions	O
change	O
with	O
the	O
mode	O
,	O
sometimes	O
acting	O
as	O
menu	O
navigation	O
keys	O
as	O
well	O
.	O
</s>
<s>
HP	B-General_Concept
2640	I-General_Concept
series	O
terminals	O
(	O
1975	O
)	O
:	O
first	O
known	O
instancelate	O
1970sof	O
screen-labeled	B-General_Concept
function	I-General_Concept
keys	I-General_Concept
(	O
where	O
keys	O
are	O
placed	O
in	O
proximity	O
or	O
mapped	O
to	O
labels	O
on	O
CRT	O
or	O
LCD	B-Device
screen	I-Device
)	O
.	O
</s>
<s>
HP	B-Device
9830	I-Device
:	O
F1	O
–	O
F8	O
on	O
two	O
rows	O
of	O
four	O
in	O
upper	O
left	O
with	O
paper	O
template	O
label	O
.	O
</s>
<s>
An	O
early	O
use	O
of	O
function	B-Application
keys	I-Application
(	O
1972	O
)	O
.	O
</s>
<s>
IBM	B-Operating_System
3270	I-Operating_System
:	O
probably	O
the	O
origin	O
of	O
function	B-Application
keys	I-Application
on	O
keyboards	B-Device
,	O
circa	O
1972	O
.	O
</s>
<s>
On	O
this	O
mainframe	O
keyboard	B-Device
early	O
models	O
had	O
12	O
function	B-Application
keys	I-Application
in	O
a	O
3×4	O
matrix	O
at	O
the	O
right	O
of	O
the	O
keyboard	B-Device
;	O
later	O
that	O
changed	O
to	O
a	O
numeric	B-Device
keypad	I-Device
,	O
and	O
the	O
function	B-Application
keys	I-Application
moved	O
to	O
the	O
top	O
of	O
the	O
keyboard	B-Device
,	O
and	O
increased	O
to	O
24	O
keys	O
in	O
two	O
rows	O
.	O
</s>
<s>
IBM	B-Device
5250	I-Device
:	O
early	O
models	O
frequently	O
had	O
a	O
"	O
cmd	O
"	O
modifier	O
key	O
,	O
by	O
which	O
the	O
numeric	O
row	O
keys	O
emulate	O
function	B-Application
keys	I-Application
;	O
later	O
models	O
have	O
either	O
12	O
function	B-Application
keys	I-Application
in	O
groups	O
of	O
4	O
(	O
with	O
shifted	O
keys	O
acting	O
as	O
F13	O
–	O
F24	O
)	O
,	O
or	O
24	O
in	O
two	O
rows	O
.	O
</s>
<s>
IBM	B-Device
PC	I-Device
AT	I-Device
and	I-Device
PS/2	I-Device
keyboard	I-Device
:	O
F1	O
to	O
F12	O
usually	O
in	O
three	O
4-key	O
groups	O
across	O
the	O
top	O
of	O
the	O
keyboard	B-Device
.	O
</s>
<s>
The	O
original	O
IBM	B-Device
PC	I-Device
and	O
PC	B-Device
XT	I-Device
keyboards	B-Device
had	O
function	B-Application
keys	I-Application
F1	O
through	O
F10	O
,	O
in	O
two	O
adjacent	O
vertical	O
columns	O
on	O
the	O
left	O
hand	O
side	O
;	O
F1|F2	O
,	O
F3|F4	O
,	O
...	O
,	O
F9|F10	O
,	O
descending	O
.	O
</s>
<s>
Some	O
IBM	O
compatible	O
keyboards	B-Device
,	O
e.g.	O
,	O
the	O
Northgate	O
OmniKey/102	O
,	O
also	O
featured	O
function	B-Application
keys	I-Application
on	O
the	O
left	O
,	O
which	O
on	O
examples	O
with	O
swapped	O
left	O
Alt	O
and	O
Caps	O
Lock	O
keys	O
,	O
facilitate	O
fingers	O
of	O
a	O
single	O
hand	O
simultaneously	O
striking	O
modifier	O
key(s )	O
and	O
function	B-Application
keys	I-Application
swiftly	O
and	O
comfortably	O
by	O
touch	O
even	O
by	O
those	O
with	O
small	O
hands	O
.	O
</s>
<s>
Many	O
modern	O
PC	B-Device
keyboards	I-Device
also	O
include	O
specialized	O
keys	O
for	O
multimedia	O
and	O
operating	O
system	O
functions	O
.	O
</s>
<s>
MCK-142	O
Pro	O
:	O
two	O
sets	O
of	O
function	B-Application
keys	I-Application
:	O
F1	O
–	O
F12	O
at	O
the	O
left	O
side	O
of	O
the	O
keyboard	B-Device
and	O
additionally	O
24	O
user	O
programmable	O
PF	B-Application
keys	I-Application
located	O
above	O
QWERTY	O
keys	O
.	O
</s>
<s>
NEC	B-Device
PC-8000	I-Device
Series	I-Device
(	O
1979	O
)	O
:	O
five	O
function	B-Application
keys	I-Application
at	O
the	O
top	O
of	O
the	O
keyboard	B-Device
,	O
along	O
with	O
a	O
numeric	B-Device
keypad	I-Device
on	O
the	O
right-hand	O
side	O
of	O
the	O
keyboard	B-Device
.	O
</s>
<s>
Sharp	O
MZ-700	O
:	O
blue	O
keys	O
F1	O
to	O
F5	O
in	O
a	O
horizontal	O
row	O
across	O
the	O
top	O
left	O
side	O
of	O
the	O
keyboard	B-Device
,	O
the	O
keys	O
are	O
vertically	O
half	O
the	O
size	O
of	O
ordinary	O
keys	O
and	O
twice	O
the	O
width	O
;	O
there	O
is	O
also	O
a	O
dedicated	O
"	O
slot	O
"	O
for	O
changeable	O
key	O
legend	O
overlays	O
(	O
paper/plastic	O
)	O
above	O
the	O
function	B-Application
key	I-Application
row	O
.	O
</s>
<s>
VT100	B-Device
terminals	O
:	O
four	O
function	B-Application
keys	I-Application
(	O
PF1	O
-	O
PF4	O
)	O
above	O
the	O
numeric	B-Device
keypad	I-Device
.	O
</s>
<s>
In	O
the	O
classic	B-Application
Mac	I-Application
OS	I-Application
,	O
the	O
function	B-Application
keys	I-Application
could	O
be	O
configured	O
by	O
the	O
user	O
,	O
with	O
the	O
Function	B-Application
Keys	I-Application
control	O
panel	O
,	O
to	O
start	O
a	O
program	O
or	O
run	O
an	O
AppleScript	B-Application
.	O
</s>
<s>
macOS	B-Application
assigns	O
default	O
functionality	O
to	O
(	O
almost	O
)	O
all	O
the	O
function	B-Application
keys	I-Application
from	O
to	O
,	O
but	O
the	O
actions	O
assigned	O
by	O
default	O
to	O
these	O
function	B-Application
keys	I-Application
has	O
changed	O
a	O
couple	O
of	O
times	O
over	O
the	O
history	O
of	O
Mac	B-Device
products	O
and	O
corresponding	O
Mac	B-Application
OS	I-Application
X	I-Application
versions	O
.	O
</s>
<s>
As	O
a	O
consequence	O
,	O
the	O
labels	O
on	O
Macintosh	B-Device
keyboards	B-Device
have	O
changed	O
over	O
time	O
to	O
reflect	O
the	O
newer	O
mappings	O
of	O
later	O
Mac	B-Application
OS	I-Application
X	I-Application
versions	O
:	O
for	O
instance	O
,	O
on	O
a	O
2006	O
MacBook	O
Pro	O
,	O
functions	O
keys	O
,	O
and	O
are	O
labelled	O
for	O
volume	O
down/volume	O
up	O
,	O
whereas	O
on	O
later	O
MacBook	O
Pros	O
(	O
starting	O
with	O
the	O
2007	O
model	O
)	O
,	O
the	O
volume	O
controls	O
are	O
located	O
on	O
function	B-Application
keys	I-Application
to	O
where	O
they	O
are	O
mapped	O
to	O
various	O
functions	O
.	O
</s>
<s>
Any	O
recent	O
version	O
of	O
Mac	B-Application
OS	I-Application
X	I-Application
or	O
macOS	B-Application
is	O
able	O
to	O
detect	O
which	O
generation	O
of	O
Apple	B-Device
keyboard	I-Device
is	O
being	O
used	O
,	O
and	O
to	O
assign	O
proper	O
default	O
actions	O
corresponding	O
to	O
the	O
labels	O
shown	O
on	O
this	O
Apple	B-Device
keyboard	I-Device
(	O
provided	O
that	O
this	O
keyboard	B-Device
was	O
manufactured	O
before	O
the	O
release	O
of	O
the	O
version	O
of	O
Mac	B-Application
OS	I-Application
X	I-Application
being	O
used	O
)	O
.	O
</s>
<s>
not	O
matching	O
the	O
labels	O
shown	O
on	O
the	O
keyboard	B-Device
)	O
when	O
using	O
a	O
recent	O
USB	O
Apple	B-Device
keyboard	I-Device
on	O
an	O
older	O
version	O
of	O
Mac	B-Application
OS	I-Application
X	I-Application
which	O
does	O
n't	O
know	O
about	O
the	O
new	O
function	B-Application
key	I-Application
mapping	O
of	O
this	O
keyboard	B-Device
(	O
e.g.	O
</s>
<s>
because	O
Mission	O
control	O
and	O
Launchpad	O
did	O
n't	O
exist	O
at	O
that	O
time	O
,	O
the	O
corresponding	O
labels	O
shown	O
on	O
the	O
keyboard	B-Device
ca	O
n't	O
match	O
the	O
default	O
actions	O
assigned	O
by	O
older	O
versions	O
of	O
Mac	B-Application
OS	I-Application
X	I-Application
which	O
were	O
Exposé	O
and	O
Dashboard	O
)	O
.	O
</s>
<s>
all	O
function	B-Application
keys	I-Application
have	O
been	O
changed	O
over	O
time	O
,	O
to	O
the	O
exception	O
of	O
and	O
who	O
have	O
always	O
been	O
mapped	O
to	O
brightness	O
control	O
.	O
</s>
<s>
all	O
Apple	O
laptops	O
after	O
2007	O
are	O
missing	O
any	O
Num	B-Device
Lock	I-Device
key	I-Device
,	O
even	O
if	O
they	O
lack	O
a	O
keypad	O
(	O
the	O
Num	B-Device
Lock	I-Device
was	O
previously	O
located	O
on	O
the	O
key	O
on	O
older	O
Apple	O
laptops	O
)	O
.	O
</s>
<s>
the	O
special	O
key	O
for	O
ejection	O
of	O
disks	O
(	O
which	O
was	O
located	O
at	O
the	O
right	O
of	O
the	O
key	O
on	O
older	O
Apple	B-Device
keyboards	I-Device
)	O
has	O
been	O
removed	O
from	O
Apple	O
computers	O
since	O
they	O
do	O
n't	O
have	O
an	O
internal	O
optical	O
disk	O
drive	O
anymore	O
,	O
to	O
the	O
exception	O
of	O
the	O
MacBook	O
Air	O
2010	O
which	O
had	O
disk	O
ejection	O
labelled	O
on	O
its	O
key	O
(	O
for	O
use	O
in	O
combination	O
with	O
an	O
external	O
USB	O
SuperDrive	O
)	O
.	O
</s>
<s>
function	B-Application
keys	I-Application
to	O
have	O
no	O
labels	O
;	O
they	O
were	O
only	O
available	O
on	O
full	O
keyboards	B-Device
of	O
fixed	O
Apple	O
computers	O
(	O
iMac	O
,	O
Mac	B-Device
Pro	O
,	O
or	O
Mac	B-Device
Mini	O
)	O
.	O
</s>
<s>
All	O
laptop	O
computers	O
have	O
always	O
lacked	O
these	O
extra	O
keys	O
,	O
as	O
well	O
as	O
any	O
recent	O
fixed	O
Apple	O
computer	O
equipped	O
with	O
wireless	O
Apple	B-Device
keyboard	I-Device
.	O
</s>
<s>
on	O
some	O
macOS	B-Application
versions	O
,	O
it	O
's	O
said	O
that	O
function	B-Application
keys	I-Application
and	O
are	O
mapped	O
by	O
default	O
to	O
decrease/increase	O
contrast	O
(	O
although	O
nothing	O
is	O
labelled	O
on	O
these	O
keys	O
on	O
Macintosh	B-Device
keyboards	B-Device
)	O
.	O
</s>
<s>
on	O
all	O
versions	O
of	O
Mac	B-Application
OS	I-Application
X	I-Application
or	O
macOS	B-Application
,	O
software	O
functions	O
can	O
be	O
used	O
by	O
holding	O
down	O
the	O
Fn	B-Device
key	I-Device
while	O
pressing	O
the	O
appropriate	O
function	B-Application
key	I-Application
,	O
and	O
this	O
scheme	O
can	O
be	O
reversed	O
by	O
changing	O
the	O
macOS	B-Application
system	O
preferences	O
.	O
</s>
<s>
as	O
of	O
2016	O
,	O
Apple	O
has	O
replaced	O
the	O
individual	O
function	B-Application
keys	I-Application
with	O
the	O
touchbar	O
on	O
certain	O
models	O
of	O
MacBook	O
Pro	O
.	O
</s>
<s>
Under	O
MS-DOS	B-Application
,	O
individual	O
programs	O
could	O
decide	O
what	O
each	O
function	B-Application
key	I-Application
meant	O
to	O
them	O
,	O
and	O
the	O
command	B-Application
line	I-Application
had	O
its	O
own	O
actions	O
(	O
e.g.	O
,	O
copied	O
to	O
the	O
current	O
command	B-Device
prompt	O
words	O
from	O
the	O
previous	O
command	B-Device
)	O
.	O
</s>
<s>
Following	O
the	O
IBM	B-General_Concept
Common	I-General_Concept
User	I-General_Concept
Access	I-General_Concept
guidelines	O
,	O
the	O
key	O
gradually	O
became	O
universally	O
associated	O
with	O
Help	O
in	O
most	O
early	O
Windows	O
programs	O
.	O
</s>
<s>
To	O
this	O
day	O
,	O
Microsoft	B-Application
Office	I-Application
programs	O
running	O
in	O
Windows	O
list	O
as	O
the	O
key	O
for	O
Help	O
in	O
the	O
Help	O
menu	O
.	O
</s>
<s>
Some	O
applications	O
such	O
as	O
Visual	B-Application
Studio	I-Application
support	O
+	O
as	O
a	O
means	O
of	O
searching	O
for	O
the	O
currently	O
highlighted	O
text	O
elsewhere	O
in	O
a	O
document	O
.	O
</s>
<s>
is	O
also	O
commonly	O
used	O
as	O
a	O
reload	O
key	O
in	O
many	O
web	B-Application
browsers	I-Application
and	O
other	O
applications	O
,	O
while	O
activates	O
the	O
full	O
screen/kiosk	O
mode	O
on	O
most	O
browsers	B-Application
.	O
</s>
<s>
is	O
used	O
in	O
many	O
Windows	B-Application
applications	I-Application
such	O
as	O
Windows	O
Explorer	O
,	O
Excel	O
,	O
Visual	B-Application
Studio	I-Application
and	O
other	O
programs	O
to	O
access	O
file	O
or	O
field	O
edit	O
functions	O
.	O
</s>
<s>
Other	O
function	B-Application
key	I-Application
assignments	O
common	O
to	O
all	O
Microsoft	B-Application
Office	I-Application
applications	O
are	O
:	O
to	O
check	O
spelling	O
,	O
+	O
to	O
call	O
the	O
macros	O
dialog	O
,	O
+	O
to	O
call	O
the	O
Visual	O
Basic	O
Editor	O
and	O
++	O
to	O
call	O
the	O
Script	O
Editor	O
.	O
</s>
<s>
WordPerfect	O
for	O
DOS	O
is	O
an	O
example	O
of	O
a	O
program	O
that	O
made	O
heavy	O
use	O
of	O
function	B-Application
keys	I-Application
.	O
</s>
<s>
In	O
Internet	B-Application
Explorer	I-Application
6	I-Application
and	O
Internet	B-Application
Explorer	I-Application
7	I-Application
,	O
opens	O
Internet	B-Application
Explorer	I-Application
Developer	I-Application
Toolbar	I-Application
.	O
</s>
<s>
Function	B-Application
Keys	I-Application
are	O
also	O
heavily	O
used	O
in	O
the	O
BIOS	B-Operating_System
interface	O
.	O
</s>
<s>
Generally	O
during	O
the	O
power-on	B-Device
self-test	I-Device
,	O
BIOS	B-Operating_System
access	O
can	O
be	O
gained	O
by	O
hitting	O
either	O
a	O
function	B-Application
key	I-Application
or	O
the	O
delete	O
key	O
.	O
</s>
<s>
In	O
the	O
BIOS	B-Operating_System
keys	O
can	O
have	O
different	O
purposes	O
depending	O
on	O
the	O
BIOS	B-Operating_System
.	O
</s>
<s>
During	O
Windows	B-Operating_System
10	I-Operating_System
startup	O
,	O
+	O
is	O
used	O
to	O
enter	O
safe	B-Operating_System
mode	I-Operating_System
;	O
in	O
legacy	O
versions	O
of	O
Microsoft	B-Application
Windows	I-Application
,	O
the	O
key	O
was	O
used	O
alone	O
.	O
</s>
