<s>
Selections	B-General_Concept
,	O
cut	O
buffers	O
,	O
and	O
drag-and-drop	O
are	O
the	O
mechanisms	O
used	O
in	O
the	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
to	O
allow	O
a	O
user	O
to	O
transfer	O
data	O
from	O
one	O
window	O
to	O
another	O
.	O
</s>
<s>
Selections	B-General_Concept
and	O
cut	O
buffer	O
are	O
typically	O
used	O
when	O
a	O
user	O
selects	O
text	O
or	O
some	O
other	O
data	O
in	O
a	O
window	O
and	O
pastes	O
in	O
another	O
one	O
.	O
</s>
<s>
Since	O
the	O
two	O
windows	O
may	O
be	O
handled	O
by	O
two	O
different	O
applications	O
,	O
these	O
mechanisms	O
require	O
two	O
different	O
clients	O
connected	O
with	O
the	O
same	O
X	B-Operating_System
server	O
to	O
exchange	O
data	O
.	O
</s>
<s>
The	O
X	B-Device
Window	I-Device
System	I-Device
core	I-Device
protocol	I-Device
includes	O
some	O
requests	O
and	O
events	O
that	O
are	O
specific	O
to	O
selection	O
exchange	O
,	O
but	O
the	O
transfer	O
is	O
mainly	O
done	O
using	O
event	O
sending	O
and	O
window	B-Device
properties	I-Device
,	O
which	O
are	O
not	O
specific	O
to	O
selection	O
transfer	O
.	O
</s>
<s>
Selections	B-General_Concept
and	O
drag-and-drop	O
are	O
active	O
mechanisms	O
:	O
after	O
some	O
text	O
is	O
selected	O
in	O
a	O
window	O
,	O
the	O
client	O
handling	O
the	O
window	O
must	O
actively	O
support	O
a	O
protocol	O
for	O
transferring	O
the	O
data	O
to	O
the	O
application	O
requesting	O
it	O
.	O
</s>
<s>
The	O
X	B-Operating_System
clipboard	O
is	O
a	O
passive	O
mechanism	O
as	O
perceived	O
by	O
the	O
client	O
holding	O
the	O
selection	O
,	O
but	O
requires	O
the	O
xclipboard	O
client	O
to	O
actively	O
support	O
any	O
subsequent	O
data	O
transfer	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
piece	O
of	O
text	O
rendering	O
HTML	B-Language
code	I-Language
can	O
be	O
transferred	O
as	O
text	O
to	O
a	O
requester	O
that	O
can	O
only	O
handle	O
text	O
,	O
but	O
can	O
also	O
be	O
transferred	O
as	O
HTML	B-Language
code	I-Language
if	O
the	O
requester	O
can	O
handle	O
it	O
.	O
</s>
<s>
The	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
supports	O
an	O
arbitrary	O
number	O
of	O
selections	B-General_Concept
;	O
every	O
selection	O
is	O
identified	O
by	O
a	O
string	O
(	O
more	O
precisely	O
,	O
an	O
atom	O
)	O
.	O
</s>
<s>
This	O
protocol	O
involves	O
the	O
second	O
and	O
third	O
requests	O
of	O
the	O
list	O
above	O
,	O
and	O
is	O
not	O
specified	O
by	O
the	B-Protocol
X	I-Protocol
protocol	I-Protocol
but	O
as	O
a	O
convention	O
in	O
the	O
Inter-Client	B-Operating_System
Communication	I-Operating_System
Convention	I-Operating_System
Manual	I-Operating_System
(	O
ICCCM	B-Operating_System
)	O
.	O
</s>
<s>
The	O
XFixes	B-Device
extension	O
allow	O
clients	O
to	O
listen	O
for	O
selection	O
changes	O
.	O
</s>
<s>
At	O
the	O
level	O
of	O
the	O
core	O
protocol	O
,	O
the	O
PRIMARY	O
and	O
CLIPBOARD	O
selections	B-General_Concept
do	O
not	O
differ	O
.	O
</s>
<s>
They	O
are	O
window	B-Device
properties	I-Device
of	O
the	O
root	B-Device
window	I-Device
,	O
named	O
CUT_BUFFER1	O
,	O
etc	O
.	O
</s>
<s>
Unlike	O
selections	B-General_Concept
,	O
cut	O
buffers	O
do	O
not	O
involve	O
a	O
direct	O
interaction	O
between	O
clients	O
.	O
</s>
<s>
Rather	O
,	O
when	O
text	O
is	O
selected	O
in	O
a	O
window	O
,	O
the	O
window	O
owner	O
copies	O
this	O
text	O
into	O
the	O
property	O
of	O
the	O
root	B-Device
window	I-Device
called	O
CUT_BUFFER1	O
.	O
</s>
<s>
When	O
the	O
user	O
pastes	O
the	O
text	O
in	O
another	O
window	O
,	O
the	O
window	O
owner	O
reads	O
this	O
property	O
of	O
the	O
root	B-Device
window	I-Device
.	O
</s>
<s>
The	O
xcutsel	O
program	O
transfers	O
data	O
between	O
selections	B-General_Concept
and	O
cut	O
buffers	O
,	O
and	O
the	O
xcb	O
program	O
allows	O
various	O
kinds	O
of	O
access	O
to	O
the	O
cut	O
buffers	O
.	O
</s>
<s>
Drag-and-drop	O
in	O
the	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
is	O
regulated	O
by	O
the	O
Xdnd	O
convention	O
.	O
</s>
<s>
The	O
Direct	B-Protocol
Save	I-Protocol
Protocol	I-Protocol
,	O
abbreviated	O
XDS	O
(	O
for	O
X	B-Operating_System
Window	I-Operating_System
Direct	B-Protocol
Save	I-Protocol
Protocol	I-Protocol
)	O
,	O
is	O
a	O
software	O
protocol	O
that	O
supports	O
saving	O
files	O
by	O
dragging	O
them	O
to	O
file	B-Application
manager	I-Application
windows	O
.	O
</s>
<s>
,	O
,	O
xsel	O
and	O
are	O
command	O
line	O
programs	O
that	O
copy	O
data	O
to	O
or	O
from	O
the	O
X	B-Operating_System
selection	O
.	O
</s>
<s>
xcopy	O
has	O
a	O
verbosity	O
option	O
that	O
helps	O
debug	O
X	B-Operating_System
selection	O
issues	O
.	O
</s>
<s>
parcellite	B-Language
also	O
has	O
the	O
ability	O
to	O
read	O
from	O
and	O
write	O
to	O
specific	O
X	B-Operating_System
selections	B-General_Concept
from	O
the	O
command	O
line	O
.	O
</s>
