<s>
An	O
aperture	B-Application
card	I-Application
is	O
a	O
type	O
of	O
punched	B-Architecture
card	I-Architecture
with	O
a	O
cut-out	O
window	O
into	O
which	O
a	O
chip	O
of	O
microfilm	O
is	O
mounted	O
.	O
</s>
<s>
Such	O
a	O
card	O
is	O
used	O
for	O
archiving	B-Application
or	O
for	O
making	O
multiple	O
inexpensive	O
copies	O
of	O
a	O
document	O
for	O
ease	O
of	O
distribution	O
.	O
</s>
<s>
The	O
microfilm	O
chip	O
is	O
most	O
commonly	O
35mm	O
in	O
height	O
,	O
and	O
contains	O
an	O
optically	B-Algorithm
reduced	I-Algorithm
image	O
,	O
usually	O
of	O
some	O
type	O
of	O
reference	O
document	O
,	O
such	O
as	O
an	O
engineering	B-Architecture
drawing	I-Architecture
,	O
that	O
is	O
the	O
focus	O
of	O
the	O
archiving	B-Application
process	O
.	O
</s>
<s>
Aperture	B-Application
cards	I-Application
have	O
several	O
advantages	O
and	O
disadvantages	O
when	O
compared	O
to	O
digital	O
systems	O
.	O
</s>
<s>
While	O
many	O
aperture	B-Application
cards	I-Application
still	O
play	O
an	O
important	O
role	O
in	O
archiving	B-Application
,	O
their	O
role	O
is	O
gradually	O
being	O
replaced	O
by	O
digital	O
systems	O
.	O
</s>
<s>
Aperture	B-Application
cards	I-Application
are	O
used	O
for	O
engineering	B-Architecture
drawings	I-Architecture
from	O
all	O
engineering	O
disciplines	O
.	O
</s>
<s>
The	O
U.S.	O
Department	O
of	O
Defense	O
once	O
made	O
extensive	O
use	O
of	O
aperture	B-Application
cards	I-Application
,	O
and	O
some	O
are	O
still	O
in	O
use	O
,	O
but	O
most	O
data	O
is	O
now	O
digital	O
.	O
</s>
<s>
Aperture	B-Application
cards	I-Application
have	O
,	O
for	O
archival	O
purposes	O
,	O
some	O
advantages	O
over	O
digital	O
systems	O
.	O
</s>
<s>
Aperture	B-Application
cards	I-Application
created	O
from	O
35mm	O
roll	O
film	O
mounted	O
on	O
to	O
blank	O
cards	O
have	O
to	O
be	O
treated	O
with	O
great	O
care	O
.	O
</s>
<s>
Machines	O
are	O
now	O
available	O
that	O
scan	B-Application
aperture	B-Application
cards	I-Application
and	O
produce	O
a	O
digital	O
version	O
.	O
</s>
<s>
Aperture	B-Application
card	I-Application
plotters	O
are	O
machines	O
that	O
use	O
a	O
laser	O
to	O
create	O
the	O
image	O
on	O
the	O
film	O
.	O
</s>
<s>
Aperture	B-Application
cards	I-Application
can	O
be	O
converted	O
to	O
digital	O
documents	O
using	O
scanning	O
equipment	O
and	O
software	O
.	O
</s>
