<s>
An	O
RDF	B-Language
query	I-Language
language	I-Language
is	O
a	O
computer	B-Language
language	I-Language
,	O
specifically	O
a	O
query	B-Language
language	I-Language
for	O
databases	O
,	O
able	O
to	O
retrieve	O
and	O
manipulate	O
data	O
stored	O
in	O
Resource	O
Description	O
Framework	O
(	O
RDF	O
)	O
format	O
.	O
</s>
<s>
SPARQL	B-Language
has	O
emerged	O
as	O
the	O
standard	O
RDF	B-Language
query	I-Language
language	I-Language
,	O
and	O
in	O
2008	O
became	O
a	O
W3C	O
recommendation	O
.	O
</s>
<s>
Properties	O
relevant	O
to	O
RDF	B-Language
query	I-Language
language	I-Language
design	O
include	O
support	O
for	O
the	O
RDF	O
format	O
:	O
</s>
<s>
RDF	B-Language
query	I-Language
languages	I-Language
can	O
be	O
grouped	O
into	O
language	O
families	O
,	O
each	O
family	O
comprising	O
a	O
set	O
of	O
closely	O
related	O
languages	O
.	O
</s>
<s>
The	O
SPARQL	B-Language
family	O
of	O
languages	O
includes	O
SquishQL	O
,	O
RDQL	B-Language
,	O
SPARQL	B-Language
,	O
and	O
TriQL	O
.	O
</s>
<s>
Members	O
of	O
the	O
SPARQL	B-Language
family	O
are	O
considered	O
relational	O
query	B-Language
languages	I-Language
because	O
they	O
have	O
relational	O
or	O
pattern-based	O
operations	O
.	O
</s>
<s>
RDQL	B-Language
,	O
an	O
acronym	O
for	O
RDF	O
Data	O
Query	B-Language
Language	I-Language
,	O
was	O
a	O
further	O
development	O
of	O
SquishQL	O
.	O
</s>
<s>
RDQL	B-Language
was	O
intended	O
to	O
be	O
a	O
simple	O
low	O
level	O
RDF	O
language	O
and	O
was	O
at	O
one	O
point	O
a	O
candidate	O
for	O
W3C	O
standardization	O
.	O
</s>
<s>
SPARQL	B-Language
is	O
an	O
extension	O
of	O
RDQL	B-Language
that	O
supports	O
extraction	O
of	O
RDF	O
subgraphs	O
.	O
</s>
<s>
In	O
2008	O
,	O
SPARQL	B-Language
1.0	O
became	O
a	O
W3C	O
recommendation	O
and	O
SPARQL	B-Language
1.1	O
became	O
a	O
W3C	O
recommendation	O
in	O
2013	O
.	O
</s>
<s>
RQL	O
,	O
an	O
acronym	O
for	O
RDF	B-Language
Query	I-Language
Language	I-Language
,	O
is	O
known	O
for	O
using	O
types	O
defined	O
in	O
RDF	O
schemas	O
(	O
RDFS	O
)	O
to	O
query	O
the	O
schema	O
class	O
hierarchy	O
and	O
to	O
support	O
data	O
querying	O
by	O
type	O
.	O
</s>
<s>
RQL	O
is	O
considered	O
more	O
expressive	O
than	O
the	O
SPARQL	B-Language
family	O
of	O
languages	O
,	O
but	O
has	O
been	O
criticized	O
for	O
too	O
many	O
features	O
and	O
unusual	O
syntactic	O
constructs	O
.	O
</s>
<s>
There	O
is	O
a	O
family	O
of	O
RDF	B-Language
query	I-Language
languages	I-Language
inspired	O
by	O
XML	B-Protocol
query	O
technology	O
.	O
</s>
<s>
XQuery	B-Language
for	O
RDF	O
uses	O
the	O
XML	B-Language
query	I-Language
language	I-Language
XQuery	B-Language
to	O
query	O
RDF	O
data	O
by	O
serializing	O
RDF	O
into	O
an	O
XML	B-Protocol
format	O
and	O
then	O
using	O
XQuery	B-Language
on	O
the	O
result	O
;	O
this	O
has	O
been	O
called	O
the	O
"	O
syntactic	O
web	O
approach	O
"	O
.	O
</s>
<s>
TreeHugger	O
and	O
RDF	O
Twig	O
use	O
XSLT	B-Application
to	O
query	O
RDF	O
data	O
.	O
</s>
<s>
Versa	O
by	O
4Suite	O
is	O
a	O
query	B-Language
language	I-Language
that	O
drew	O
inspiration	O
from	O
XPath	B-Language
.	O
</s>
<s>
There	O
exist	O
RDF	B-Language
query	I-Language
languages	I-Language
based	O
on	O
other	O
principles	O
.	O
</s>
<s>
Algae	O
is	O
a	O
query	B-Language
language	I-Language
developed	O
by	O
the	O
W3C	O
that	O
adds	O
reactive	O
rules	O
,	O
also	O
called	O
actions	O
,	O
that	O
determine	O
for	O
instance	O
whether	O
an	O
Algae	O
expression	O
is	O
a	O
data	O
query	O
or	O
a	O
data	O
update	O
.	O
</s>
<s>
Other	O
examples	O
of	O
RDF	B-Language
Query	I-Language
languages	I-Language
include	O
RDFDBQL	O
.	O
</s>
<s>
XUL	B-Application
has	O
a	O
element	O
in	O
which	O
to	O
declare	O
rules	O
for	O
matching	O
data	O
in	O
RDF	O
.	O
</s>
<s>
XUL	B-Application
uses	O
RDF	O
extensively	O
for	O
databinding	O
.	O
</s>
<s>
XQuery	B-Language
,	O
or	O
XML	B-Protocol
Query	O
,	O
is	O
a	O
standard	O
query	B-Language
language	I-Language
for	O
XML	B-Protocol
documents	I-Protocol
.	O
</s>
<s>
Graph	O
query	B-Language
languages	I-Language
,	O
such	O
as	O
Cypher	B-Language
Query	I-Language
Language	I-Language
,	O
GraphQL	B-Language
,	O
and	O
Gremlin	O
,	O
are	O
designed	O
to	O
query	O
graph	B-Application
databases	I-Application
,	O
of	O
which	O
RDF	O
data	O
stores	O
are	O
an	O
example	O
.	O
</s>
<s>
The	O
Topic	B-Application
Map	I-Application
Query	B-Language
Language	I-Language
(	O
TMQL	O
)	O
is	O
a	O
query	B-Language
language	I-Language
for	O
topic	B-Application
maps	I-Application
,	O
a	O
data	O
representation	O
similar	O
to	O
but	O
more	O
general	O
than	O
RDF	O
.	O
</s>
