<s>
The	O
Data	B-Application
Documentation	I-Application
Initiative	I-Application
(	O
also	O
known	O
as	O
DDI	O
)	O
is	O
an	O
international	O
standard	O
for	O
describing	O
surveys	O
,	O
questionnaires	O
,	O
statistical	O
data	O
files	O
,	O
and	O
social	O
sciences	O
study-level	O
information	O
.	O
</s>
<s>
The	O
DDI	O
specification	O
,	O
most	O
often	O
expressed	O
in	O
XML	B-Protocol
,	O
provides	O
a	O
format	O
for	O
content	O
,	O
exchange	O
,	O
and	O
preservation	O
of	O
questionnaire	O
and	O
data	O
file	O
information	O
.	O
</s>
