<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
link	B-Application
time	I-Application
refers	O
to	O
the	O
period	O
of	O
time	O
,	O
during	O
the	O
creation	O
of	O
a	O
computer	B-Application
program	I-Application
,	O
in	O
which	O
a	O
linker	B-Application
is	O
being	O
applied	O
to	O
that	O
program	B-Application
.	O
</s>
<s>
Link	B-Application
time	I-Application
occurs	O
after	O
compile	B-Application
time	I-Application
and	O
before	O
runtime	B-Library
(	O
when	O
a	O
program	B-Application
is	O
executed	B-General_Concept
)	O
.	O
</s>
<s>
It	O
is	O
common	O
to	O
speak	O
of	O
link	B-Application
time	I-Application
operations	O
(	O
the	O
operations	O
performed	O
by	O
a	O
linker	B-Application
)	O
or	O
link	B-Application
time	I-Application
requirements	O
(	O
programming	O
language	O
requirements	O
that	O
must	O
be	O
met	O
by	O
compiled	O
source	O
code	O
for	O
it	O
to	O
be	O
successfully	O
linked	O
)	O
.	O
</s>
<s>
The	O
operations	O
performed	O
at	O
link	B-Application
time	I-Application
usually	O
include	O
fixing	O
up	O
the	O
addresses	O
of	O
externally	O
referenced	O
objects	O
and	O
functions	O
,	O
various	O
kinds	O
of	O
cross	O
module	O
checks	O
(	O
e.g.	O
</s>
<s>
type	O
checks	O
on	O
externally	O
visible	O
identifiers	O
and	O
in	O
some	O
languages	O
instantiation	B-Language
of	I-Language
templates	I-Language
)	O
.	O
</s>
<s>
Some	O
optimizing	B-Application
compilers	I-Application
delay	O
code	O
generation	O
until	O
link	B-Application
time	I-Application
because	O
it	O
is	O
here	O
that	O
information	O
about	O
a	O
complete	O
program	B-Application
is	O
available	O
to	O
them	O
.	O
</s>
<s>
Resolving	O
external	O
variables	O
in	O
a	O
program	B-Application
is	O
also	O
done	O
at	O
link	B-Application
time	I-Application
.	O
</s>
<s>
The	O
link-time	B-Application
optimization	O
(	O
LTO	O
)	O
,	O
when	O
enabled	O
,	O
occurs	O
at	O
link	B-Application
time	I-Application
.	O
</s>
<s>
The	O
definition	O
of	O
a	O
programming	O
language	O
may	O
specify	O
link	B-Application
time	I-Application
requirements	O
that	O
source	O
code	O
must	O
meet	O
to	O
be	O
successfully	O
compiled	O
(	O
e.g.	O
</s>
<s>
In	O
some	O
programming	O
languages	O
it	O
may	O
be	O
necessary	O
for	O
some	O
compilation	O
and	O
linking	B-Application
to	O
occur	O
at	B-Library
runtime	I-Library
.	O
</s>
