<s>
OpenCards	B-Language
is	O
a	O
free	B-Application
spaced	O
repetition	O
flashcard	O
program	O
.	O
</s>
<s>
The	O
software	O
is	O
similar	O
to	O
SuperMemo	B-Application
,	O
Anki	B-Application
or	O
Mnemosyne	B-Language
.	O
</s>
<s>
The	O
flashcards	O
are	O
saved	O
as	O
PowerPoint	B-Application
presentation	O
files	O
and	O
may	O
include	O
text	O
,	O
images	O
,	O
sounds	O
and	O
LaTeX	B-Application
equations	O
.	O
</s>
<s>
OpenCards	B-Language
implements	O
learning	O
schemes	O
for	O
short-term	O
and	O
long-term	O
memorization	O
.	O
</s>
<s>
OpenCards	B-Language
uses	O
PowerPoint	B-Application
ppt-files	O
as	O
flashcard	O
sets	O
.	O
</s>
<s>
OpenCards	B-Language
also	O
supports	O
a	O
reversed	O
mode	O
in	O
which	O
slide	O
contents	O
are	O
treated	O
as	O
questions	O
and	O
the	O
slide	O
title	O
as	O
their	O
answers	O
,	O
which	O
allows	O
creating	O
image	O
,	O
formula	O
or	O
sound	O
questions	O
.	O
</s>
<s>
By	O
allowing	O
users	O
to	O
create	O
flashcard	O
files	O
in	O
ppt-format	O
with	O
PowerPoint	B-Application
or	O
LibreOffice	B-Application
,	O
it	O
overcomes	O
the	O
major	O
limitation	O
of	O
other	O
flashcard	O
software	O
,	O
which	O
usually	O
rely	O
on	O
custom	O
formats	O
and	O
flashcard	O
editors	O
.	O
</s>
<s>
Internally	O
,	O
OpenCards	B-Language
relies	O
on	O
Apache	B-Language
POI	I-Language
to	O
render	O
slides	O
from	O
ppt-files	O
.	O
</s>
<s>
OpenCards	B-Language
implements	O
two	O
different	O
learning	O
models	O
.	O
</s>
<s>
The	O
SM2	O
algorithm	O
had	O
been	O
created	O
for	O
SuperMemo	B-Application
in	O
the	O
late	O
1980s	O
,	O
but	O
still	O
forms	O
the	O
basis	O
of	O
many	O
spaced	O
repetition	O
software	O
applications	O
.	O
</s>
<s>
OpenCards	B-Language
's	O
implementation	O
of	O
the	O
algorithm	O
has	O
been	O
modified	O
to	O
allow	O
priorities	O
on	O
cards	O
,	O
and	O
to	O
show	O
cards	O
in	O
order	O
of	O
their	O
urgency	O
.	O
</s>
<s>
OpenCards	B-Language
started	O
as	O
flashcard	O
learning	O
extension	O
for	O
OpenOffice	O
Impress	O
in	O
spring	O
2008	O
,	O
from	O
which	O
it	O
inherited	O
the	O
first	O
part	O
of	O
its	O
name	O
.	O
</s>
<s>
In	O
2011	O
,	O
OpenCards	B-Language
was	O
redesigned	O
to	O
work	O
as	O
stand	O
alone	O
software	O
and	O
to	O
support	O
PowerPoint	B-Application
PPT	O
files	O
as	O
the	O
main	O
flashcard	O
set	O
file	O
format	O
.	O
</s>
<s>
OpenCards	B-Language
implements	O
no	O
synchronization	O
mechanism	O
,	O
but	O
flashcard	O
sets	O
including	O
their	O
learning	O
states	O
can	O
be	O
synced	O
using	O
services	O
like	O
DropBox	B-Application
.	O
</s>
