<s>
Extensible	B-Language
Forms	I-Language
Description	I-Language
Language	I-Language
(	O
XFDL	B-Language
)	O
is	O
a	O
high-level	O
computer	B-Language
language	I-Language
that	O
facilitates	O
defining	O
a	O
form	O
as	O
a	O
single	O
,	O
stand-alone	O
object	O
using	O
elements	O
and	O
attributes	O
from	O
the	O
Extensible	B-Protocol
Markup	I-Protocol
Language	I-Protocol
(	O
XML	B-Protocol
)	O
.	O
</s>
<s>
Technically	O
,	O
it	O
is	O
a	O
class	O
of	O
XML	B-Protocol
originally	O
specified	O
in	O
a	O
World	O
Wide	O
Web	O
Consortium	O
(	O
W3C	O
)	O
Note	O
.	O
</s>
<s>
See	O
Specifications	O
below	O
for	O
links	O
to	O
the	O
current	O
versions	O
of	O
XFDL	B-Language
.	O
</s>
<s>
XFDL	B-Language
It	O
offers	O
precise	O
control	O
over	O
form	O
layout	O
,	O
permitting	O
replacement	O
of	O
existing	O
business/government	O
forms	O
with	O
electronic	O
documents	O
in	O
a	O
human-readable	O
,	O
open	O
standard	O
.	O
</s>
<s>
In	O
addition	O
to	O
precision	O
layout	O
control	O
,	O
XFDL	B-Language
provides	O
multiple	O
page	O
capabilities	O
,	O
step-by-step	O
guided	O
user	O
experiences	O
,	O
and	O
digital	O
signatures	O
.	O
</s>
<s>
XFDL	B-Language
also	O
provides	O
a	O
syntax	O
for	O
in-line	O
mathematical	O
and	O
conditional	O
expressions	O
and	O
data	O
validation	O
constraints	O
as	O
well	O
as	O
custom	O
items	O
,	O
options	O
,	O
and	O
external	O
code	O
functions	O
.	O
</s>
<s>
Current	O
versions	O
of	O
XFDL	B-Language
(	O
see	O
Specifications	O
below	O
)	O
are	O
capable	O
of	O
providing	O
these	O
interactive	O
features	O
via	O
open	O
standard	O
markup	O
languages	O
including	O
XForms	O
,	O
XPath	O
,	O
XML	B-Protocol
Schema	O
and	O
XML	B-Protocol
Signatures	O
.	O
</s>
<s>
XFDL	B-Language
not	O
only	O
supports	O
multiple	O
digital	O
signatures	O
,	O
but	O
the	O
signatures	O
can	O
apply	O
to	O
specific	O
sections	O
of	O
a	O
form	O
and	O
prevent	O
changes	O
to	O
signed	O
content	O
.	O
</s>
<s>
These	O
advantages	O
to	O
XFDL	B-Language
led	O
large	O
organizations	O
such	O
as	O
the	O
United	O
States	O
Army	O
and	O
Air	O
Force	O
to	O
migrate	O
to	O
XFDL	B-Language
from	O
using	O
forms	O
in	O
other	O
formats	O
.	O
</s>
<s>
Later	O
,	O
though	O
,	O
the	O
lack	O
of	O
portable	O
software	O
capable	O
of	O
creating	O
XFDL	B-Language
led	O
them	O
to	O
investigate	O
moving	O
away	O
from	O
it	O
.	O
</s>
<s>
The	O
Army	O
migrated	O
to	O
Adobe	O
fillable	O
PDFs	B-Application
in	O
2014	O
.	O
</s>
