<s>
A	O
name	B-Application
–	I-Application
value	I-Application
pair	I-Application
,	O
also	O
called	O
an	O
attribute	B-Application
–	I-Application
value	I-Application
pair	I-Application
,	O
key	B-Application
–	I-Application
value	I-Application
pair	I-Application
,	O
or	O
field	B-Application
–	I-Application
value	I-Application
pair	I-Application
,	O
is	O
a	O
fundamental	O
data	B-General_Concept
representation	I-General_Concept
in	O
computing	O
systems	O
and	O
applications	B-Application
.	O
</s>
<s>
Designers	O
often	O
desire	O
an	O
open-ended	O
data	B-General_Concept
structure	I-General_Concept
that	O
allows	O
for	O
future	B-General_Concept
extension	I-General_Concept
without	O
modifying	O
existing	O
code	O
or	O
data	O
.	O
</s>
<s>
In	O
such	O
situations	O
,	O
all	O
or	O
part	O
of	O
the	O
data	B-Application
model	I-Application
may	O
be	O
expressed	O
as	O
a	O
collection	O
of	O
2-tuples	B-Application
in	O
the	O
form	O
attribute	O
name	O
,	O
value	O
with	O
each	O
element	O
being	O
an	O
attribute	B-Application
–	I-Application
value	I-Application
pair	I-Application
.	O
</s>
<s>
Some	O
of	O
the	O
applications	B-Application
where	O
information	O
is	O
represented	O
as	O
attribute	B-Application
–	I-Application
value	I-Application
pairs	I-Application
are	O
:	O
</s>
<s>
Some	O
computer	B-Language
languages	I-Language
implement	O
attribute	B-Application
–	I-Application
value	I-Application
pairs	I-Application
,	O
or	O
more	O
frequently	O
collections	O
of	O
attribute	B-Application
–	I-Application
value	I-Application
pairs	I-Application
,	O
as	O
standard	O
language	O
features	O
.	O
</s>
<s>
Most	O
of	O
these	O
implement	O
the	O
general	O
model	O
of	O
an	O
associative	B-Application
array	I-Application
:	O
an	O
unordered	O
list	O
of	O
unique	O
attributes	O
with	O
associated	O
values	O
.	O
</s>
<s>
In	O
some	O
applications	B-Application
,	O
an	O
attribute	B-Application
–	I-Application
value	I-Application
pair	I-Application
has	O
a	O
value	O
that	O
contains	O
a	O
nested	B-General_Concept
collection	O
of	O
attribute	B-Application
–	I-Application
value	I-Application
pairs	I-Application
.	O
</s>
<s>
Some	O
data	B-Application
serialization	I-Application
formats	O
such	O
as	O
JSON	B-General_Concept
support	O
arbitrarily	O
deep	O
nesting	B-General_Concept
.	O
</s>
<s>
Other	O
data	O
representations	O
are	O
restricted	O
to	O
one	O
level	O
of	O
nesting	B-General_Concept
,	O
such	O
as	O
INI	B-Protocol
file	I-Protocol
's	O
section/name/value	O
.	O
</s>
