<s>
A	O
soft	B-General_Concept
key	I-General_Concept
is	O
a	O
button	O
flexibly	O
programmable	O
to	O
invoke	O
any	O
of	O
a	O
number	O
of	O
functions	O
rather	O
than	O
being	O
associated	O
with	O
a	O
single	O
fixed	O
function	O
or	O
a	O
fixed	O
set	O
of	O
functions	O
.	O
</s>
<s>
A	O
softkey	B-General_Concept
often	O
takes	O
the	O
form	O
of	O
a	O
screen-labeled	O
function	B-Application
key	I-Application
located	O
alongside	O
a	O
display	B-Device
device	I-Device
,	O
where	O
the	O
button	O
invokes	O
a	O
function	O
described	O
by	O
the	O
text	O
at	O
that	O
moment	O
shown	O
adjacent	O
to	O
the	O
button	O
on	O
the	O
display	O
.	O
</s>
<s>
Soft	B-General_Concept
keys	I-General_Concept
are	O
also	O
found	O
away	O
from	O
the	O
display	B-Device
device	I-Device
,	O
for	O
example	O
on	O
the	O
sides	O
of	O
cellular	O
phones	O
,	O
where	O
they	O
are	O
typically	O
programmed	O
to	O
invoke	O
functions	O
such	O
as	O
PTT	O
,	O
memo	O
,	O
or	O
volume	O
control	O
.	O
</s>
<s>
Function	B-Application
keys	I-Application
on	O
keyboards	B-Device
are	O
a	O
form	O
of	O
soft	B-General_Concept
key	I-General_Concept
.	O
</s>
<s>
In	O
contrast	O
,	O
a	O
hard	B-General_Concept
key	I-General_Concept
is	O
a	O
key	O
with	O
dedicated	O
function	O
such	O
as	O
the	O
keys	O
on	O
a	O
number	O
keypad	O
.	O
</s>
<s>
Screen-labeled	B-General_Concept
function	I-General_Concept
keys	I-General_Concept
are	O
today	O
most	O
commonly	O
found	O
in	O
kiosk	O
applications	O
,	O
such	O
as	O
automated	O
teller	O
machines	O
and	O
gas	O
pumps	O
.	O
</s>
<s>
Screen-label	O
function	B-Application
keys	I-Application
date	O
to	O
aviation	O
applications	O
in	O
the	O
late	O
1960s	O
.	O
</s>
<s>
Screen-labeled	B-General_Concept
function	I-General_Concept
keys	I-General_Concept
are	O
found	O
in	O
automotive	O
and	O
aviation	O
applications	O
such	O
as	O
in	O
the	O
primary	O
flight	O
and	O
multi-function	B-Device
displays	I-Device
.	O
</s>
<s>
An	O
alternative	O
to	O
screen-labeled	B-General_Concept
function	I-General_Concept
keys	I-General_Concept
is	O
buttons	O
(	O
virtual	O
keys	O
)	O
on	O
a	O
touchscreen	B-Device
,	O
where	O
the	O
label	O
is	O
directly	O
pushable	O
.	O
</s>
<s>
The	O
increased	O
prevalence	O
of	O
touchscreens	B-Device
in	O
the	O
2000s	O
has	O
led	O
to	O
a	O
decrease	O
in	O
screen-labeled	B-General_Concept
function	I-General_Concept
keys	I-General_Concept
.	O
</s>
<s>
However	O
,	O
screen-labeled	B-General_Concept
function	I-General_Concept
keys	I-General_Concept
are	O
inexpensive	O
and	O
robust	O
,	O
and	O
provide	O
tactile	O
feedback	O
.	O
</s>
<s>
Early	O
examples	O
are	O
found	O
in	O
aviation	O
glass	B-Device
cockpits	I-Device
,	O
such	O
as	O
the	O
Mark	O
II	O
avionics	O
of	O
the	O
F-111D	O
in	O
the	O
late	O
1960s/early	O
1970s	O
(	O
first	O
ordered	O
1967	O
,	O
delivered	O
1970	O
–	O
73	O
)	O
.	O
</s>
<s>
The	O
HP	B-Device
9830	I-Device
desktop	O
computer	O
was	O
the	O
first	O
calculator	O
with	O
two	O
rows	O
of	O
4	O
keys	O
,	O
over	O
which	O
a	O
paper	O
overlay	O
would	O
be	O
placed	O
.	O
</s>
<s>
Programmers	O
found	O
that	O
the	O
HP	B-General_Concept
2640	I-General_Concept
terminals	O
could	O
lock	O
the	O
top	O
two	O
lines	O
of	O
the	O
screen	O
,	O
so	O
they	O
displayed	O
the	O
key	O
functions	O
there	O
.	O
</s>
<s>
Starting	O
with	O
HP	B-General_Concept
2647	I-General_Concept
terminal	O
,	O
the	O
keys	O
were	O
re-arranged	O
to	O
correspond	O
with	O
2	O
pairs	O
of	O
4	O
labels	O
at	O
the	O
bottom	O
of	O
the	O
screen	O
.	O
</s>
<s>
This	O
would	O
be	O
further	O
developed	O
on	O
the	O
failed	O
HP	B-Device
300	I-Device
Amigo	O
,	O
which	O
used	O
keys	O
at	O
the	O
right	O
side	O
of	O
the	O
screen	O
and	O
HP	B-Device
250	I-Device
business	O
computers	O
which	O
placed	O
them	O
at	O
the	O
bottom	O
.	O
</s>
<s>
They	O
are	O
rarely	O
found	O
on	O
PC	O
applications	O
,	O
even	O
though	O
the	O
first	O
IBM	O
PC	O
BASIC	O
labeled	O
function	B-Application
key	I-Application
use	O
at	O
the	O
bottom	O
of	O
the	O
screen	O
,	O
and	O
there	O
were	O
12	O
function	B-Application
keys	I-Application
,	O
patterned	O
after	O
use	O
on	O
IBM	O
terminals	O
.	O
</s>
<s>
Modern	O
Texas	O
Instruments	O
calculators	O
such	O
as	O
the	O
TI-89	B-Device
series	I-Device
use	O
function	B-Application
keys	I-Application
to	O
open	O
drop-down	O
menus	O
on	O
their	O
menu	O
bar	O
,	O
the	O
menu	O
title	O
acting	O
like	O
the	O
key	O
label	O
.	O
</s>
<s>
Casio	O
calculators	O
use	O
the	O
function	B-Application
keys	I-Application
for	O
a	O
menu	O
at	O
the	O
bottom	O
of	O
the	O
screen	O
.	O
</s>
<s>
A	O
typical	O
mobile	O
phone	O
with	O
soft	B-General_Concept
keys	I-General_Concept
has	O
them	O
located	O
beneath	O
the	O
bottom	O
left	O
and	O
bottom	O
right	O
of	O
the	O
display	O
;	O
some	O
,	O
especially	O
those	O
made	O
by	O
Nokia	O
,	O
have	O
an	O
additional	O
center	O
soft	B-General_Concept
key	I-General_Concept
,	O
activated	O
by	O
pressing	O
on	O
the	O
center	O
of	O
the	O
directional	B-Device
pad	I-Device
.	O
</s>
<s>
Usually	O
the	O
prompt	O
text	O
on	O
the	O
display	O
for	O
the	O
softkey	B-General_Concept
is	O
not	O
allowed	O
to	O
be	O
truncated	O
or	O
omitted	O
with	O
ellipsis	O
.	O
</s>
<s>
The	O
softkey	B-General_Concept
itself	O
is	O
usually	O
not	O
printed	O
with	O
a	O
functional	O
icon	O
or	O
text	O
,	O
but	O
is	O
often	O
marked	O
with	O
a	O
dot	O
or	O
short	O
bar	O
.	O
</s>
<s>
Soft	B-General_Concept
keys	I-General_Concept
have	O
become	O
increasingly	O
rare	O
as	O
touchscreens	B-Device
take	O
the	O
place	O
of	O
function	B-Application
keys	I-Application
on	O
many	O
modern	O
smartphones	B-Application
.	O
</s>
<s>
Screen-labeled	B-General_Concept
function	I-General_Concept
keys	I-General_Concept
have	O
found	O
use	O
in	O
point	O
of	O
sale	O
systems	O
;	O
NCR	O
Corporation	O
claims	O
that	O
their	O
DynaKey	O
system	O
"	O
has	O
been	O
proven	O
to	O
reduce	O
training	O
time	O
and	O
cashier	O
errors	O
"	O
.	O
</s>
