<s>
A	O
reference	B-General_Concept
card	I-General_Concept
or	O
reference	B-General_Concept
sheet	I-General_Concept
(	O
or	O
quick	B-General_Concept
reference	I-General_Concept
card	I-General_Concept
)	O
or	O
crib	O
sheet	O
is	O
a	O
concise	O
bundling	O
of	O
condensed	O
notes	O
about	O
a	O
specific	O
topic	O
,	O
such	O
as	O
mathematical	O
formulas	O
to	O
calculate	O
area/volume	O
,	O
or	O
common	O
syntactic	B-Application
rules	O
and	O
idioms	O
of	O
a	O
particular	O
computer	B-Device
platform	I-Device
,	O
application	B-Application
program	I-Application
,	O
or	O
formal	O
language	O
.	O
</s>
<s>
In	O
spite	O
of	O
what	O
the	O
name	O
reference	B-General_Concept
card	I-General_Concept
may	O
suggest	O
,	O
such	O
as	O
a	O
3x5	O
index	O
card	O
(	O
)	O
,	O
the	O
term	O
also	O
applies	O
to	O
sheets	O
of	O
paper	O
or	O
online	O
pages	O
,	O
as	O
in	O
the	O
context	O
of	O
programming	O
languages	O
or	O
markup	O
languages	O
.	O
</s>
<s>
As	O
in	O
the	O
examples	O
below	O
,	O
reference	B-General_Concept
cards	I-General_Concept
are	O
typically	O
one	O
to	O
a	O
few	O
pages	O
in	O
length	O
.	O
</s>
<s>
Terms	O
might	O
include	O
keywords	O
,	O
syntactic	B-Application
constructs	O
,	O
functions	O
,	O
methods	O
,	O
or	O
macros	O
in	O
a	O
computer	O
language	O
.	O
</s>
<s>
In	O
a	O
reference	B-General_Concept
card	I-General_Concept
for	O
a	O
program	O
with	O
a	O
graphical	O
user	O
interface	O
,	O
terms	O
may	O
include	O
menu	O
entries	O
,	O
icons	O
or	O
key	O
combinations	O
representing	O
program	O
actions	O
.	O
</s>
<s>
Due	O
to	O
its	O
logical	O
structure	O
and	O
conciseness	O
,	O
finding	O
information	O
in	O
a	O
reference	B-General_Concept
card	I-General_Concept
is	O
trivial	O
for	O
humans	O
and	O
requires	O
no	O
computer	O
interaction	O
.	O
</s>
<s>
It	O
is	O
therefore	O
convenient	O
for	O
a	O
user	O
to	O
print	O
out	O
a	O
reference	B-General_Concept
card	I-General_Concept
.	O
</s>
<s>
While	O
reference	B-General_Concept
cards	I-General_Concept
can	O
be	O
printed	O
on	O
card	O
stock	O
,	O
it	O
is	O
common	O
to	O
print	O
them	O
on	O
ordinary	O
printer	O
paper	O
.	O
</s>
<s>
With	O
the	O
advent	O
of	O
portable	O
electronic	O
devices	O
that	O
can	O
display	O
documents	O
,	O
digital	O
reference	B-General_Concept
cards	I-General_Concept
stored	O
in	O
PDF	B-Application
or	O
HTML	B-Language
formats	O
have	O
become	O
more	O
common	O
.	O
</s>
<s>
A	O
LaTeX	B-Application
reference	B-General_Concept
sheet	I-General_Concept
:	O
</s>
<s>
An	O
AMS	O
LaTeX	B-Application
reference	B-General_Concept
card	I-General_Concept
:	O
</s>
<s>
An	O
R	B-Language
reference	B-General_Concept
card	I-General_Concept
:	O
</s>
<s>
An	O
R	B-Language
reference	B-General_Concept
card	I-General_Concept
for	O
data	B-Application
mining	I-Application
:	O
</s>
<s>
A	O
CC	O
(	O
common	O
criteria	O
)	O
quick	B-General_Concept
reference	I-General_Concept
card	I-General_Concept
for	O
security	O
product	O
evaluation	O
:	O
</s>
